Title of Invention

"3,6-DISUBSTITUTED AZABICYCLO [3.1.0]HEXANE DERIVATIVES USEFUL AS MUSCARINIC RECEPTOR ANTAGONISTS"

Abstract

This invention generally relates to the derivatives of novel 3,6 disubstituted azabicyclo[3.1.0] hexanes. The compounds of this invention are muscarinic receptor antagonists which are useful, inter-alia for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The invention also relates to pharmaceutical compositions containing the compounds of the present invention and the methods of treating the diseases mediated through muscarinic receptors.

Full Text

FIELD OF THE INVENTION This invention generally relates to the derivatives of novel 3,6-disubstituted azabicyclo[3.1.0] hexanes. The compounds of this invention are muscarinic receptor antagonists which are useful, inter-alia, for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The invention also relates to pharmaceutical compositions containing the compounds of the present invention and the methods of treating the diseases mediated through muscarinic receptors. BACKGROUND OF THE INVENTION Muscarinic receptors as members of the G Protein Coupled Receptors (GPCRs) are composed of a family of 5 receptor sub-types (M1, M2, M3, M4 and M5) and are activated by the neurotransmitter acetylcholine. These receptors are widely distributed on multiple organs and tissues and are critical to the maintenance of central and peripheral cholinergic neurotransmission. The regional distribution of these receptor sub-types in the brain and other organs has been documented. For example, the M1 subtype is located primarily in neuronal tissues such as cereberal cortex and autonomic ganglia, the M2 subtype is present mainly in the heart where it mediates cholinergically induced bradycardia, and the M3 subtype is located predominantly on smooth muscle and salivary glands (Nature, 1986; 323: 411; Science, 1987; 237: 527). A review in Current opinions in Chemical Biology, 1999; 3: 426, as well as in Trends in Pharmacological Sciences, 2001; 22: 409 by Eglen et. al., describe the biological potentials of modulating muscarinic receptor subtypes by ligands in different disease conditions like Alzheimer's disease, pain, urinary disease condition, chronic obstructive pulmonary disease etc. A review in J. Med. Chem., 2000; 43: 4333 by Christian C. Felder et. al. describes therapeutic opportunities for muscarinic receptors in the central nervous system and elaborates on muscarinic receptor structure and function, pharmacology and their therapeutic uses. The pharmacological and medical aspects of the muscarinic class of acetylcholine agonists and antagonists are presented in a review in Molecules, 2001, 6: 142. N.J.M. Birdsall et. al. in Trends in Pharmacological Sciences, 2001; 22: 215 have also summarized the recent developments on the role of different muscarinic receptor subtypes using different muscaranic receptor of knock out mice. Muscarinic agonists such as muscarine and pilocarpine and antagonists such as atropine have been known for over a century, but little progress has been made in the discovery of receptor subtype-selective compounds making it difficult to assign specific functions to the individual receptors. Although classical muscarinic antagonists such as atropine are potent bronchodilators, their clinical utility is limited due to high incidence of both peripheral and central adverse effects such as tachycardia, blurred vision, dryness of mouth, constipation, dementia, etc. Subsequent development of the quarterly derivatives of atropine such as ipratropium bromide are better tolerated than parenterally administered options but most of them are not ideal anti-cholinergic bronchodilators due to lack of selectivity for muscarinic receptor sub-types. The existing compounds offer limited therapeutic benefit due to their lack of selectivity resulting in dose limiting side-effects such as thirst, nausea, mydriasis and those associated with the heart such as tachycardia mediated by the M2 receptor. Annual review of Pharmacological Toxicol., 2001; 41: 691, describes the pharmacology of the lower urinary tract infections. Although anti muscarinic agents such as oxybutynin and tolterodine that act non-selectively on muscarinic receptors have been used for many years to treat bladder hyperactivity, the clinical effectiveness of these agents has been limited due to the side effects such as dry mouth, blurred vision and constipation. Tolterodine is considered to be generally better tolerated than oxybutynin. (W.D.Steers et. al. in Curr. Opin. Invest. Drugs, 2: 268, C.R. Chappie et. al. in Urology, 55: 33), Steers WD, Barrot DM, Wein AJ, 1996, Voiding dysfunction: diagnosis classification and management. In Adult and Pediatric Urology, ed. JY Gillenwatter, JT Grayhack, SS Howards, JW Duckett, pp 1220-1325, St. Louis, MO; Mosby. 3rd edition.) Despite these advances, there remains a need for development of new highly selective muscarinic antagonists which can interact with distinct subtypes, thus avoiding the occurrence of adverse effects. Compounds having antagonistic activity against muscarinic receptors have been described in Japanese patent application Laid Open Number 92921/1994 and 135958/1994; WO 93/16048; U.S. Patent No. 3,176,019; GB 940,540; EP 0325 571; WO 98/29402; EP 0801067; EP 0388054; WO 9109013; U.S. Patent No. 5,281,601. U.S. Patent Nos. 6,174,900, 6,130,232 and 5,948,792; WO 97/45414 are related to 1,4-disubstituted piperidine derivatives; WO 98/05641 describes fluorinated, 1,4-disubstitued piperidine derivatives; and W096/33973 are other close art references. A report in J. Med. Chem., 2002; 44:984, describes cyclohexylmethyl piperidinyl triphenylpropioamide derivatives as selective M3 antagonist discriminating against the other receptor subtypes. SUMMARY OF THE INVENTION The present invention provides novel 3,6-disubstituted azabicyclo[3.1.0]hexanes as muscarinic receptor antagonists which are useful as safe and effective therapeutic or prophylactic agents for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems, and process for the synthesis of the novel compounds. The invention also provides pharmaceutical compositions containing the novel compounds together with acceptable carriers, excipients or diluents which are useful for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems. The present invention also includes within its scope prodrugs of the novel compounds. In general, such prodrugs will be functionalized derivatives of these compounds which readily get converted in vivo into the defined compounds. Conventional procedures for the selection and preparation of suitable prodrugs are known to the artisan skilled in the art. The invention also includes the enantiomers, diastereomers, N-oxides, polymorphs, pharmaceutically acceptable salts and pharmaceutically acceptable solvates of these compounds as well as metabolites having the same type of activity. The invention further includes pharmaceutical compositions comprising the compounds of the present invention, their prodrugs, metabolites, enantiomers, diastereomers, N-oxides, polymorphs, solvates or pharmaceutically acceptable salts thereof, in combination with a pharmaceutically acceptable carrier and optionally included excipients. Other advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description or may be learnt by the practice of the invention. The objects and the advantages of the invention may be realized and obtained by means of the mechanisms and combinations pointed out in the appended claims. In accordance with one aspect of the present invention, there is provided a compound having the structure of Formula I: (Formula Removed) and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar represents an aryl or a heteroaryl ring having 1-2 hetero atoms selected from the group consisting of oxygen, sulphur and nitrogen atoms, the aryl or heteroaryl rings may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C1-C4), lower perhalo alkyl (C1-C4), cyano, hydroxy, nitro, lower alkoxy (C1-C4), lower perhalo alkoxy (C1-C4), unsubstituted amino, N-lower alkyl (C1-C4) amino or N-lower alkyl (C1-C4) amino carbonyl; Ri represents a hydrogen, hydroxy, hydroxy methyl, amino, alkoxy, carbamoyl or halogen (e.g. fluorine, chlorine, bromine and iodine); R.2 represents alkyl, C3-C7 cycloalkyl ring, a C3-C7 cyclo alkenyl ring, an aryl or a heteroaryl ring having 1 to 2 hetero atoms selected from a group consisting of oxygen, sulphur and nitrogen atoms; the aryl or a heteroaryl ring may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C1-C4), lower perhalo alkyl (C1-C4), cyano, hydroxy, nitro, lower alkoxycarbonyl, halogen, lower alkoxy (C1-C4), lower perhalo alkoxy (C1- C4), unsubstituted amino, N-lower alkylamino (C1-C4), N-lower alkylamino carbonyl (C1-C4); W represents (CH2)P, where p represents 0 to 1; X represents an oxygen, sulphur, nitrogen or no atom; Y represents CHR5CO wherein R5 represents hydrogen or methyl or (CH2)q wherein q represents 0 to 4; Z represents oxygen, sulphur, NR10, wherein R10 represents hydrogen, C1-6 alkyl; Q represents (CH2)n wherein n represents 0 to 4, or CHR8 wherein R8 represents H, OH, C1-6, alkyl, alkenyl alkoxy or CH2CHR9 wherein R9 represents H, OH , lower alkyl (CrC4) or lower alkoxy (C1-C4); R6 and R7 are independently selected from COOH, H, CH3, CONH2, NH2, CH2NH2; R4 represents C1-C15 saturated or unsaturated aliphatic hydrocarbon groups in which any 1 to 6 hydrogen atoms may be substituted with the group independently selected from halogen, arylalkyl, arylalkenyl, heteroarylalkyl or heteroarylalkenyl having 1 to 2 hetero atoms selected from a group consisting of nitrogen, oxygen and sulphur atoms with option that any 1 to 3 hydrogen atoms on the ring in said arylalkyl, arylalkenyl, hetero arylalkenyl group may be substituted with lower alkyl (C1-C4), lower perhalo alkyl (C1-C4), cyano, hydroxyl, nitro, lower alkoxycarbonyl, halogen, lower alkoxy (C1-C4), lower perhaloalkoxy (C1-C4), unsubstituted amino, N-lower alkylamino (C1-C4), N-lower alkylamino carbonyl (C1-C4). In accordance with a second aspect of the present invention, there is provided a compound having the structure of Formula II (Formula I, when R6 and R7 = H) and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar, R1, R2, W, X, Y, Z, Q and R4 are as defined for Formula I. (Formula Removed) In accordance with a third aspect of the present invention, there is provided a compound having the structure of Formula III (Formula I wherein W is (CH2)p where p - 0, X is no atom and Y is (CH2)q where q = 0, R$ = H, R7 = H) and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar, Ri, R2, Z, Q and R4 are as defined for Formula I. (Formula Removed) In accordance with a fourth aspect of the present invention, there is provided a compound having the structure of Formula IV (Formula I wherein W is (CH2)p where p = 0, X is no atom and Y is (CH2)q where q = 0, R6 = H, R7 = H, R2 =) and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar, R1, Z, Q and R4 are as defined for Formula I and r is 1 to 4. (Formula Removed) In accordance with a fifth aspect of the present invention, there is provided a compound having the structure of Formula V (Formula I wherein W is (CF^p where p = 0, X is no atom and Y is (CH2)q where q=0, R$ = H, R7 = H, R2 = LX Ri is hydroxy, Ar is phenyl), and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein R4, Z and Q are the same as defined for Formula I, s represents 1 to2. (Formula Removed) In accordance with a sixth aspect of the present invention, there is provided a method for treatment or prophylaxis of an animal or a human suffering from a disease or disorder of the respiratory, urinary and gastrointestinal systems, wherein the disease or disorder is mediated through muscarinic receptors. In accordance with a seventh aspect of the present invention, there is provided a method for treatment or prophylaxis of an animal or a human suffering from a disease or disorder associated with muscarinic receptors, comprising administering to a patient in need thereof, an effective amount for muscarinic receptor antagonist compound as described above. In accordance with an eighth aspect of the present invention, there is provided a method for treatment or prophylaxis of an animal or a human suffering from a disease or disorder of the respiratory system such as bronchial asthma, chronic obstructive pulmonary disorders (COPD), pulmonary fibrosis, etc.; urinary system which induce such urinary disorders as urinary incontinence, lower urinary tract symptoms (LUTS), etc.; and gastrointestinal system such as irritable bowel syndrome, obesity, diabetes and gastrointestinal hyperkinesis with compounds as described above, wherein the disease or disorder is associated with muscarinic receptors. In accordance with a ninth aspect of the present invention, there are provided processes for preparing the compounds as described above. The compounds of the present invention are novel and exhibit significant potency in terms of their activity, which was determined by in vitro receptor binding and functional assays and in vivo experiments using anaesthetized rabbit. The compounds that were found active in in vitro assay were tested in vivo. Some of the compounds of the present invention were found to be potent muscarinic receptor antagonists with high affinity towards M3 receptors. Therefore, the present invention provides the pharmaceutical compositions for the possible treatment for the disease or disorders associated with muscarinic receptors. In addition, the compounds of the present invention can be administered orally or parenterally. DETAILED DESCRIPTION OF THE INVENTION The compounds of the present invention may be prepared by techniques well known in the art and familiar to the average synthetic organic chemist. In addition, the compounds of the present invention may be prepared by the following novel and inventive reaction sequences: (Scheme Removed) The compounds of Formula I of the present invention may be prepared by the reaction sequence as shown in Scheme I. The preparation comprises condensing a compound of Formula VII (Ar, R1, R2, W are the same as defined earlier) with the compound of Formula VI (wherein P is any protecting group for an amino group including benzyl and t-butyloxy carbonyl groups, X, Y, Z, Q, R6 and R7 are the same as defined earlier) in the presence of a condensing agent to give a protected compound of Formula VIII which on deprotection in the presence of a deprotecting agent in an organic solvent gives an unprotected intermediate of Formula IX which is finally N-alkylated or benzylated with a suitable alkylating or benzylating agent L-R4 to give a compound of Formula I (wherein L is any leaving group and R4 is as defined above). The reaction of the compound of Formula VII with a compound of Formula VI to give a compound of Formula VIII is carried out in the presence of a condensing agent which is selected from the group consisting of l-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride (EDC) and 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU). The reaction of the compound of Formula VII with a compound of Formula VI to give a compound of Formula VIII is carried out in a suitable solvent selected from the group consisting of N,N-dimethylformamide, dimethylsulfoxide, toluene, and xylene at a temperature ranging from about 0-140°C. The deprotection of the compound of Formula VIII to give a compound of Formula IX is carried out with a deprotecting agent which is selected from the group consisting of palladium on carbon, trifluoroacetic acid (TFA) and hydrochloric acid. The deprotection of the compound of Formula VIII to give a compound of Formula IX is carried out in a suitable organic solvent selected from the group consisting of methanol, ethanol, tetrahydrofuran and acetonitrile at temperatures ranging from about 10-50°C. The N-alkylation or benzylation of the compound of Formula IX to give a compound of Formula I is carried out with a suitable alkylating or benzylating agent, L-R4 wherein L is any leaving group, known in the art, preferably selected from halogen, O-mestyl and O-tosyl group. The N-alkylation or benzylation of the compound of Formula IX to give a compound of Formula I is carried out in a suitable organic solvent such as N,N-dimethylforrnamide, dimethyl sulfoxide, tetrahydrofuran and acetonitrile, at temperatures ranging from about 25-100°C. In the above scheme, where specific bases, condensing agents, protecting groups, deprotecting agents, N-alkylating/benzylating agents, solvents, catalysts etc. are mentioned, it is to be understood that other bases, condensing agents, protecting groups, deprotecting agents, N-alkylating/benzylating agents, solvents, catalysts etc. known to those skilled in the art may be used. Similarly, the reaction temperature and duration may be adjusted according to the desired needs. Alternatively, the compounds of the invention may be prepared by condensing compounds of formula VI with an aryl alpha keto ester (Ar(CO)COOR' wherin R' denotes a lower alkyl group) and the compounds thus formed may be subsequently reacted with the condensate R"M , wherein R" groups include groups such as phenyl, C4-6 alkyl etc. and M may be alkali metal or MgX, wherein x is a halogen atom. Alpha keto esters may in turn be prepared by following J.O.C., 46,213(1981), or synthetic communication, 11, 943(1981). The compounds of the invention may also be prepared by reacting R"M (wherein M and R" have the same as described above) with the aryl alpha keto ester (Ar(CO)COOR' wherin R' denotes a lower alkyl group) to form an alpha hydroxy ester. This product is further reacted with compound of formula VI and then the protecting group is removed to give compounds of formula VIII. Suitable salts of the compounds represented by the Formula I were prepared so as to solubilize the compound in aqueous medium for biological evaluations. Examples of such salts include pharmacologically acceptable salts such as inorganic acid salts (e.g. hydrochloride, hydrobromide, sulphate, nitrate and phosphorate), organic acid salts (e.g. acetate, tartarate, citrate, fumarate, maleate, tolounesulphonate and methanesulphonate). When carboxyl group is included in the Formula I as a substituent, it may be an alkali metal salt(e.g. sodium, potassium, calcium, magnesium, and the like). These salts may be prepared by the usual prior art techniques, such as treating the compound with an equivalent amount of inorganic or organic, acid or base in a suitable solvent. Preferred compounds according to the invention and capable of being produced by Scheme I as shown in Table-I include: Compound Chemical Name No. 1. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide 2. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 3. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 4. (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2-diphenyl acetate 5. (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate 6. (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 7. (1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2 -phenyl acetate 8. (1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 9. (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 10. (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 11. (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 12. (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate 13. (1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 14. (1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 15. (1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 16. (1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 17. (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate 18. (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 19. (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 20. (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate 21. (1α,5α,6α)-N- [3 -(1 -phenylethyl)-3 -azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 22. (1α,5α,6α)-N-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 23. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide 24. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 25. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 26. (1α,5α,6α)-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate 27. (1α,5α,6α)-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 28. (2R)-(+)- (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 29. (2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 30. (2R) (+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate 31. (2R) (+)- (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 32. (2S)-(-)- (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 33. (2S)-(-)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 34. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide L-(+)-tartrate salt 35. (2R)-(+)- (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide. L-( + )-tartrate salt 36. (2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. L-( + )-tartrate salt 37. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclobutyl-2 -phenyl acetamide 38. (1α,5α,6α)-N- [3 -benzyl-3 -azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl] -2-hydroxy-2-cyclopropyl-2-phenyl acetamide 39. (1α,5α,6α)-N-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-hexyl-2-phenyl acetamide 40. (la,5a,6cc)-[ 3-(3,4- methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate 41. (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate. L-( + )-tartrate salt 42. (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2 diphenyl acetate L(+)-tartrate salt 43. (lα,5α,6α)- [3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2- phenyl acetate L(+)-tartrate salt 44. (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2- phenyl acetate L(+)-tartrate salt. 45. (1α,5α,6α)-N-[3 -(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2- hydroxy-2-cyclohexyl-2-phenyl acetamide 46. (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetatamide 47. (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 48. (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 49. (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide 50. (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide 51. (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide 52. (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 53. (1α,5α,6α)-N- [3 -(3 -pyridylmethyl)-3 -azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl] -2-hydroxy-2-cyclopentyl-2-phenyl acetamide 54. (1α,5α,6α)-N-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 55. (1α,5α,6α)-N- [3 -(3,4-methylenedioxyphenyl)methyl-3 -azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide 56. (1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide 57. (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate- L-(+) tartrate salt 58. (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate. L-(+) tartrate salt 59. (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate. L-(+) tartrate salt 60. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide hydrochloride salt 61. (1α,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide L-(-) malic acid salt 62. (lα,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide maleate salt Because of their valuable pharmacological properties, the compounds of the present invention may be administered to an animal for treatment orally, or by parenteral route. The pharmaceutical compositions of the present invention are preferably produced and administered in dosage units, each unit containing a certain amount of at least one compound of the invention and/or at least one physiologically acceptable addition salt thereof. The dosage may be varied over extremely wide limits as the compounds are effective at low dosage levels and relatively free of toxicity. The compounds may be administered in the low micromolar concentration, which is therapeutically effective, and the dosage may be increased as desired up to the maximum dosage tolerated by the patient. The present invention also includes within its scope prodrugs of the compounds of Formulae I, II, III, IV and V. In general, such prodrugs will be functional derivatives of these compounds, which readily are converted in vivo into the defined compounds. Conventional procedures for the selection and preparation of suitable prodrugs are known. The present invention also includes the enantiomers, diastereomers, N-Oxides, polymorphs, solvates and pharmaceutically acceptable salts of these compounds as well as metabolites having the same type of activity. The present invention further includes pharmaceutical composition comprising the molecules of Formulae I, II, III, IV and V or prodrugs, metabolites, enantiomers, diastereomers, N-oxides, polymorphs, solvates or pharmaceutically acceptable salts thereof, in combination with pharmaceutically acceptable carrier and optionally included excipient. The examples mentioned below demonstrate the general synthetic procedure as well as the specific preparation of the preferred compound. The examples are provided to illustrate the details of the invention and should not be constrained to limit the scope of the present invention. EXPERIMENTAL DETAILS Various solvents, such as acetone, methanol, pyridine, ether, tetrahydrofuran, hexanes, and dichloromethane, were dried using various drying reagents according to the procedure described in the literature. IR spectra were recorded as nujol mulls or a thin neat film on a Perkin Elmer Paragon instrument, Nuclear Magnetic Resonance (NMR) were recorded on a Varian XL-300 MHz instrument using tetramethylsilane as an internal standard. EXAMPLE 1 Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicydo[3.1.0]hexyl-6-(aminomethyl)-yl]-2- hydroxy-2,2-diphenyl acetamide (Compound No.l) Step a: Preparation of 2-hydroxy-2,2-diphenyl acetic acid : Synthesized as per reported procedures in Vogel's textbook of practical organic chemistry page 1046 ( 5th Ed); J.Am.Chem.Soc, 75.2654(1953) and EP 613232. Step b: Preparation of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane : Synthesized as per reported procedures described in EP 0 413 455 ; US Patent No. 2,490,714 and Synlett, 1097-1102(1996). Step c: To a solution of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane (lmmol, 0.202 gm) in dimethyl formamide, DMF (5 ml) was added 2-hydroxy-2,2-diphenyl acetic acid (1 mmol, 0.225 gm) and cooled to 0°C. The reaction mixture was treated with hydroxy benzotriazole (1 mmol, 0.135 g) followed by N-methyl morpholine (2 mmol, 0.202 gm) and stirred at 0°C for 0.5 hrs. EDC (l-[3-(dimethylamino)propyl]-3-ethyl carbodiimide hydrochloride (lmmol,. 0.192 gms) was added and the reaction mixture (RM) was stirred at 0°C for 1 hour and at room temperature (RT) overnight. The RM was then poured into cold water and extracted with ethyl acetate. The combined organic layers were washed with water and dried over sodium sulphate. The crude compound obtained after removing the solvent was purified by column chromatography (silicagel 100-200 mesh), eluting the compound with 30-70 ethyl acetate- hexane mixture. 1H-NMR (CDCl3) δ-values : 7.47 - 7.17 (m, arom, 15H), 3.58 (s, 2H, benzylic), 3.18-3.14 (t, 2H), 2.95-2.92 (d, 2H), 2.35-2.32 (m, 2H), 2.04 (s, 1H) 1.28-1.23 (m, 1H), 0.94-0.91 (m, 2H) IR (DCM) : 1658 cm-1 (amide carbonyl) EXAMPLE 2 Preparation of (lα,5α‫,6α)-N-[3-benzyI-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No.2) Step a: Preparation of 2-hydroxy-2-cyclohexyl phenyl acetic acid: This was prepared following the procedure described in J. Amer. Chem. Soc. 75, 2654 (1953). Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2- hydroxy-2-cyclohexyl-2-phenyl acetamide To a solution of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane (lmmol, 0.202gm) in dimethyl formamide (5 ml) was added 2-hydroxy-2-cyclohexyl-2-phenylacetic acid (lmmol, 0.234gm) and cooled to 0°C. The reaction mixture was treated with hydroxy benzotriazole (lmmol, 0.135g) followed by N-methyl morpholine (2mmol, 0.202 gm) and stirred at 0°C for 0.5 hours. EDC (1 mmol, 0.192 gm) was then added. The reaction mixture (RM) after being stirred at 0°C for 1 hour was later stirred at RT overnight. The RM was poured into cold water and extracted with ethyl acetate. The organic layer was dried and the crude product obtained after removing the solvent was purified by column chromatography (Silicagel 100-200 mesh) eluting the compound with 30-70 ethyl acetate-hexane mixture. 1H-NMR: (CDCl3) δ-values : 7.61-7.11 (m, 10H), 3.55 (s, 2H), 2.92- 2.88 (m, 4H ), 2.32-2.29 (m,2H), 1.37-1.16 (m, 14H) IR(DCM) :1653cm-1 EXAMPLE 3 Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.3) Step a: Preparation of 2-hydroxy-2-cyclopentyl phenyl acetic acid: This was prepared following the procedure described in J. Amer. Chem. Soc. 75, 2654 (1953). Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide To a solution of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane (29.9mmol, 6..05 gm) in dimethyl formamide (100 ml) was added 2-hydroxy-2-cyclopentyl-2-phenyl acetic acid (27.2 mmol, 6.0 gm) and cooled to 0°C. The reaction mixture was treated with hydroxy benzotriazole (29.9 mmol, 4.04 gm) followed by N-methyl morpholine (54.4 mmol, 5.2 gm) and was stirred at 0°C for 0.5 hrs. The reaction mixture was poured into saturated bicarbonate solution and extracted with ethyl acetate. The organic layers were washed with water and dried over sodium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography (silicagel 100-200 mesh) eluting compound with 20-80 to 25-75 ethyl acetate-hexane mixture. It gave a compound in 93-95% purity. To obtain higher purity (about 99%) of the compound it was triturated with toluene and filtered. 1H-NMR: (CDCl3) δ-values: 7.61-7.23 (m, 10H), 6.45 (bs, 1H), 3.57 (s, 2H), 3.11-2.90 (m, 4H), 2.34-2.31 (m,2H), 1.68-1.48 (m, 10H), 1.23 (m,2H). MS: (M+l) = 405.3 m.pt. 131-134°C IR(DCM): 1647,1522,1265cm-1 EXAMPLE 4 Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yI]-2-hydroxy-2,2- diphenyl acetate (Compound No.4) Step-a: Preparation of (1α,5α,6α)-3-benzyl-6-hydroxymethyl-3-azabicyclo [3.1.0] hexane synthesized as per reported procedure of EP 0 413 455 A2. Step b: Preparation of (1α,5α,6α)-3-benzyl-6-(methanesulfonyloxy)methyl-3-azabicyclo [3.1.0]hexane: A solution of the title compound of preparation of Step a of Compound 4 (0.203 g ; 1 mmol) and triethylamine ( 0.21 gms, 2 mmol) in ethyl acetate (25 ml) was cooled to -10°C and treated with methanesulfonyl chloride ( 0.17 gms, 1.5 mmol) . After stirring for one hour at -10°C, the reaction was poured into a saturated aqueous sodium bicarbonate solution. The organic layer was dried over sodium sulphate. Filtration and removal of the solvent in vacuo provided the title compound as a yellow oil, which was used as such in the following step without further purification. 1H-NMR (CDCl3) δ-values: 7.45 (m, 5 H, arom.), 4.29 (s, 2H), 3.81 (m, 2H), 3.13 (m, 4H), 2.84 (s,3H), 1.38 (m,3H) Step c: Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy- 2,2-diphenyl acetate: To a solution of 2-hydroxy-2,2-diphenyl acetic acid (lmmol, 0.228gms) in xylene was added, (1α,5α,6α)-3-benzyl-6-(methanesulfonyloxy)methyl-3-azabicyclo [3.1.0]hexane: (0.28 gms, lmmol) followed by DBU (l,8-diazabicyclo[5,4,0] undec-7rene, (2mmol, 0.305 gms) and the reaction mixture refluxed for 6 hrs. The reaction mixture was then washed with water, brine and dried over sodium sulphate. The solvents were evaporated and the crude compound thus obtained was purified by column chromatography (silicagel, 100-200 mesh) eluting the compound with 20-80, ethyl acetate hexane mixture. 1H-NMR (CDCl3) δ-values: 7.46-7.22 (m, 15 H, arom.), 4.24 (s, 1H), 4.11-4.09 (d, 2H), 3.56 (s, 2H), 2.91-2.89 (d, 2H), 2.31-2.29 (d, 2H), 1.67-1.62 (m, 1H) 1.3 (s, 2H) IR (DCM): 1724 cm-1 EXAMPLE 5 Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hy droxy-2-cyclohexyl-2-phenyl acetate (Compound No.5) This compound was prepared following the procedure as in Example 4, step c using 2-hydroxy-2-cyclohexyl phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid. 1H-NMR (CDCl3) δ-values: 7.66-7.21 (m, 10 H, arom.), 4.09-3.92 (dd, 2H), 3.69 (s,2H), 2.93 -2.89 (m, 2H), 2.33- 2.30 (m, 3H), 1.65 - 1.12 (m, 13H) IR (DCM): 1720cm-1 EXAMPLE 6 Preparation of (1 oc,5a,6a)- [3-benzyl-3-azabicyclo [3.1.0] hexyl-6-(methyl)-y 1] -2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No.6) This compound was prepared following the procedure as in Example 4, step c using 2 hydroxy-2- cyclopentyl phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid. 1H-NMR (CDCl3) δ-values: 7.67-7.20 (m, 10 H, arom.), 4.06-3.93 (dd, 2H), 3.57 (s, 2H), 2.94- 2.89 (m, 3H), 2.34- 2.30 (m, 2H), 1.63-1.27 (m, 11H) IR (DCM): 1718 cm-1 EXAMPLE 7 Preparation of (la,5a,6ot)-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yI]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No.7) The compound obtained as in Example 5 was debenzylated and then N-alkylated as given below: Step a: Preparation of (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2- cyclohexyl-2-phenyl acetate A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2- cyclohexyl-2-phenyl acetate (1mmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3hrs. The reaction mixture was filtered and concentrated to afford the title compound. 1H-NMR (CDCl3) δ-values: 7.65-7.15 (m, 5 H, arom.), 4.14-4.02 (dd, 2H), 3.14-2.94 (m, 3H), 2.29- 2.21 (m, 2H), 1.46-1.11 (m, 13H) IR (KBr): 1723 cm-1 Step b: Preparation of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran Synthesized as per reported procedure of EP 0 388 054 Al, Step c: To a solution of (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2- cyclohexyl-2-phenyl acetate (0.329 gms, lmmol) in dimethyl formamide (5 ml) was added potassium carbonate (2mmol 0.276gms), potassium iodide (lmmol 0.166gms ) and 5-(2- bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate : hexane. 1H-NMR (CDCl3) δ - values: 7.67-6.67 (m, 8 H, arom.), 4.56^1.50 (m, 2H), 4.09-3.7 (dd, 2H), 3.19-3.01 (m, 4H), 2.62-2.60 (m, 3H), 2.33-2.30 (m, 4H), 1.65-1.11 (m, 13H) IR (DCM): 1721 cm-1 EXAMPLE 8 Preparation of (1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo [3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No.8) The compound obtained as in Example 6 was debenzylated and then N-alkylated as given below: Step a: Preparation of (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2- cyclopentyl-2-phenyl acetate A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2- cyclopentyl-2-phenyl acetate (lmmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3hrs. The reaction mixture was filtered and concentrated to afford the title compound. 1H-NMR (CDCl3) δ-values: 7.66-7.26 (m, 5 H, arom.), 4.15-4.01 (dd, 2H), 3.06-2.92 (m, 3H), 2.43- 2.36 (m, 2H), 1.61-1.02 (m, 11H) IR (KBr): 1721 cm-1 Step b : To a solution of compound (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2- hydroxy-2-cyclopentyl-2-phenylacetate (0.315g, lmmol) in dimethyl formamide (5 ml) was added potassium carbonate (2mmol, 0.276gms), potassium iodide (lmmol 0.166gms ) and 5-(2- bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate : hexane. 1H-NMR (CDCl3) δ-values: 7.68-6.67 (m, 8 H, arom.), 4.56-4.50 (m, 2H), 4.07-3.97 (dd, 2H), 3.19-3.02 (m, 4H), 2.33- 2.30 (m, 6H), 1.37-1.25 (m, 11H) IR (DCM): 1719 cm-1 EXAMPLE 9 Preparation of (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(amino methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No.9) The compound obtained as in Example 2 was debenzylated and then N-alkylated as given below: Step a: Preparation of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide. A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(amino methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (lmmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3hrs. The reaction mixture was filtered and concentrated to afford the title compound. 1H-NMR (CDCl3) δ-values: 7.62-7.26 (m, 5 H, arom.), 3.15-3.09 (m, 3H), 2.95-2.8l(m, 4H), 1.71-1.2 (m, 13H) IR (KBr): 1656 cm-1 Step b: To solution of compound (1 a,5 a,6a)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]- 2-hydroxy-2-cyclohexylphenyl acetamide (0.328, lmmol) in dimethyl formamide (5ml) was added potassium carbonate (2mmol 0.276gms), potassium iodide (lmmol 0.166gms) and 5-(2- bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate : hexane. 1H-NMR (CDCl3) δ-values: 7.62-6.64 (m, 8H, arom.), 4.56-4.51 (t, 2H), 3.19-2.31 (m, 12H), 1.70-1.13 (m, 14H) IR (DCM): 1654 cm-1 (amide carbonyl) EXAMPLE 10 Preparation of (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3- azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl] -2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.10) The compound obtained as in Example 3 was debenzylated and then N-alkylated as given below: Step a: Preparation of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (lmmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3hrs. The reaction mixture was filtered and concentrated to afford the title compound. 1H-NMR (CDCl3) δ -values: 7.62-7.23 (m, 5 H, arom.), 3.13-3.07 (m, 2H), 2.95-2.81 (m, 5H), 1.34-0.87 (m, 11H) IR (KBr): 1655 cm-1 Step b : To a solution of compound (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (0.314g, lmmol) in dimethyl formamide(5 ml) was added potassium carbonate (2mmol 0.276gms), potassium iodide (lmmol 0.166gms) and 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate : hexane. 1H-NMR (CDCl3) δ-values: 7.62-6.67 (m, 8H, atom.), 4.56-4.51 (t, 2H), 3.19 -2.29 (m, 12H), 1.70-1.11 (m, 12H) IR (KBr): 1657 cm-1 EXAMPLE 11 Preparation of (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo [3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No.ll) Step a: Preparation of 3,4-methylenedioxyphenethyl bromide Synthesized as per reported procedure of EP 0 388 054 Al Step b : This compound was prepared following the procedure as in Example 8, step b, using 3,4-methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3- b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.8-6.6 (m, 8H, arom.), 6.0 (s, 2H), 4.2-3.9 (dd, 2H), 3.2-2.3 (m, 9H), 1.7-1. l(m, 11H) IR (DCM) : 1720 cm-1 EXAMPLE 12 Preparation of (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No.12) This compound was prepared following the procedure as in Example 7, step c, using 3,4-methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-bjbenzofuran. 1H-NMR (CDCl3) δ-values: 7.67-6.6 (m, 8H, arom.), 5.91 (s, 2H), 4.09-3.92 (dd, 2H), 3.03-2.99 (m, 2H), 2.61-2.59 (m, 4H), 2.32-2.28 (m, 4H) 1.65-1.1 (m, 12H). IR (DCM): 1721 cm-1 EXAMPLE 13 Preparation of (1α,5α,6α)-N- [3-(2-(3,4-methylenedioxyphenyI)ethyl)-3- azabicyclo [3.1.0] hexy l-6-(aminomethyl)-yl] -2-hydroxy-2-cyclopentyl-2-pheny 1 acetamide (Compound No.13) This compound was prepared following the procedure as in Example 10, Step b using 3,4-methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.61-6.59 (m, 8H, arom.), 5.91 (s, 2H), 3.05-2.27 (m, 11H), 1.66-1.24 (m, 11H) IR (KBr): 1657cm-1 EXAMPLE 14 Preparation of (1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenylacetamide (Compound No.14) This compound was prepared following the procedure as in Example 9, Step b using 3,4- methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3- b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.62 - 6.59 (m, 8H, arom.), 5.91 (s, 2H), 3.10-2.33 (m, 11H), 1.70 - 1.17 (m, 13H) IR (DCM): 1653cm-1 EXAMPLE 15 Preparation of (1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No.15) This compound was prepared following the procedure as in Example 9, Step b using 5-bromo-2- methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.61-6.26 (m, 5H, arom.), 5.06 (t, 1H), 2.99-2.04 (m, 12H), 1.67- 1.22 (m, 19H) IR (DCM): 1656cm-1 EXAMPLE 16 Preparation of (1α,5α,6α)-N- [3-(4-methyl-3-pentenyl)-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 16) This compound was prepared following the procedure as in Example 10, Step b using 5-bromo-2- methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.61-7.25 (m, 5H, arom.), 5.06 (t, 1H), 3.06-2.04 (m, 12H), 1.67- 1.1 (m, 16H) IR (DCM): 1652cm-1 EXAMPLE 17 Preparation of (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yI]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 17) This compound was prepared following the procedure as in Example 7, Step c using 5-bromo-2- methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran 1H-NMR (CDCl3) δ-values: 7.66-7.22 (m, 5H, arom.), 5.08 (t, 1H), 4.1-3.92 (dd, 2H), 3.0-2.97 (m, 2H), 2.27-2.08 (m, 7H), 1.65-1.11 (m, 19H ) IR (DCM) : 1721cm-1 EXAMPLE 18 Preparation of (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No.18) This compound was prepared following the procedure as in Example 8, Step b using 5-bromo-2- methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.67-7.26 (m, 5H, arom.), 5.07 (t, 1H), 4.09-3.94 (dd, 2H), 3.01- 2.08 (m, 9H), 1.68-0.97 (m, 17H ) IR (DCM): 1720cm-1 EXAMPLE 19 Preparation of (1α,5α,6α)- [3-(l -phenylethyl)-3-azabicyclo [3.1.0] hexyl-6-(methyl)-yl] -2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No.19) This compound was prepared following the procedure as in Example 8, Step b using (1- bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.67-7.25 (m, 10H, arom.), 4.06-3.93 (dd, 2H), 3.24-2.08 (m, 6H), 1.6-1.23 (m, 15H) IR (DCM): 1719cm-1 EXAMPLE 20 Preparation of (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No.20) This compound was prepared following the procedure as in Example 7, Step c using (1- bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.67-7.18 (m, 10H, arom.), 4.09-3.7 (dd, 2H), 3.24-2.11 (m, 4H), 2.63-2.37 (m, 8H), 1.64-1.1 (m, 11H ) IR (DCM): 1720cm-1 EXAMPLE 21 Preparation of (1α,5α,6α)-N-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No.21) This compound was prepared following the procedure as in Example 9, Step b using (1- bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.66-7.20 (m, 10H, arom.), 3.29-2.09 (m, 9H), 1.69-0.88 (m, 16H) IR (KBr): 1653cm-1 EXAMPLE 22 Preparation of (1α,5α,6α)-N-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyC1opentyl-2-phenyl acetamide (Compound No.22) This compound was prepared following the procedure as in Example 10, Step b using (1- bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.61-7.26 (m, 10H, arom.), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H) IR (DCM): 1651cm-1 EXAMPLE 23 Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2- hydroxy-2,2-diphenyl acetamide (Compound No.23) Step a: Preparation of (1α,5α,6α)-6-(l-hydroxyethyl)-3-benzyl-3-azabicyclo[3.1.0] hexane: (1α,5α,6α)-3-benzyl-3-azabicyclo[3.1.0]hexane-6-carboxaldehyde (synthesized as per reported procedure of EP 0 413 455 A2, 2 gm, 100 mmol) was dissolved in tetrahydrofuran (400 ml) and cooled to -70°C . Methyllithium (105 mL of a 0.98 M solution in ether, 102 mmol) was added dropwise , stirred for one hour and later allowed to attain room temperature . Saturated aqueous ammonium chloride was added to the reaction mixture , the mixture was then extracted with ethyl acetate. The combined organic layers were dried over sodium sulphate, filtered and concentrated in vacuo to provide the product as a brown oil (yield 1.68 gm). 1H-NMR (CDCl3) δ-values: 7.26 (m, 5H, arom.), 3.59 (s, 2H), 3.16 (m, 1H), 2.97 (m, 2H), 2.35 (m, 2H), 1.39 (m, 1H), 1.24 (m, 5H) Step b: Preparation of (1α,5α,6α)-3-benzyl-3-azabicyclo[3.1.0]hexane-6-methylketone Dimethylsulphoxide (1.65 ml, 23 mmol) was added to a solution of oxalyl chloride (1.1 ml, 12.65 mmol) in methylene chloride (350 ml) maintained at -70°C. A solution of the title compound of preparation step a (2.5 gm, 11.5 mmol) in methylene chloride (50 ml) was then added to the reaction mixture at -70°C. After the addition of triethylamine (6.4 ml, 46 mmol), the mixture was allowed to warm to room temperature, water was added and the organic layer was collected, dried over sodium sulphate, filtered and concentrated to provide a light brown oil. Column chromatography (eluant: 20% ethyl acetate in hexane) provided the title compound (yield 1.4 gms). 1H-NMR (CDCl3) δ - values: 7.27 (m, 5H, arom.), 3.6 (s, 2H), 3.016 (m, 2H ), 2.41 (m, 3H), 2.23 (s, 3H), 1.17 (m, 2H) IR (DCM): 1694cm-1 Step c: Preparation of (1α,5α,6α)-6-(l-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0] hexane: To a stirred solution of the title compound of preparation step b (1.2 gms, 5.5 mmol) and ammonium acetate (1.28 gms, 16.6 mmol) in methanol (50 ml) was added sodium cyanoborohydride (0.87 gms, 43.75 mmol) at room temperature. The mixture was stirred for 18 hours at the same temperature. After the addition of saturated aqueous sodium bicarbonate, methanol was evaporated and the mixture was extracted three times with dichloromethane (100 ml). The combined organic extract was dried over sodium sulphate , filtered and concentrated under vacuo to obtain the crude compound (yield: 0.8 gms) which was used in the next step without purification. 1H-NMR (CDCl3) δ- values: 7.26 (m, 5H, arom.), 3.57 (s, 2H), 2.97 (m, 2H), 2.33 (m, 2H), 2.2 (m, 1H), 1.29 to 1.13 (m, 6H) IR (DCM): 1654cm-1 Step d: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2-hydroxy-2,2-diphenylacetamide: The compound of Step-d was prepared by following the procedure described in step-c of Example 1 using (1α,5α,6α)-6-(l-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane instead of (la,5a,6cc)- 6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane. 1H-NMR (CDCl3) δ-values: 7.33 (m, 15H. atom.), 6.16 (m, 1H), 3.56 (m, 2H), 3.43 (m, 1H), 2.88 (m, 2H), 2.31 (m, 2H), 1.40 (m, 1H), 1.29 to 1.13 (m, 5H) IR (DCM): 1656cm-1 EXAMPLE 24 Preparation of (1α,5α,6α)-N- [3-benzyI-3-azabicyclo [3.1.0] hexyl-6-(l -aminoethyl)-yl] -2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No.24) This compound was prepared by following the procedure described in Step-b of Example 2, using (1α,5α,6α)-6-(l-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane instead of (loc,5oc,6a)-6- aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane. 1H-NMR (CDCl3) δ-values: 7.59 to 7.09 (m, 10H, arom.), 6.52 (m, 1H), 3.55 (m, 2H), 3.25 (m, 1H), 2.90 (m, 2H), 2.25 (m, 3H), 1.37 to 0.85 (m, 16H) IR (DCM): 1651cm-1 EXAMPLE 25 Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyI acetamide (Compound No.25) This compound was prepared by following the procedure described in Step-b of Example 3, using (1α,5α,6α)-6-(l-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane instead of (la,5a,6cc)-6- aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane. 1H-NMR (CDCl3) δ-values: 7.59 to 7.23 (m, 10H, arom.), 6.30 (m, 1H), 3.54 (s, 2H), 3.29 (m, 1H), 2.93 to 2.79 (m, 3H), 2.27 (m, 3H), 1.40 (m, 1H), 1.28 to 1.0 (m, 14H) IR (DCM): 1651cm-1 EXAMPLE 26 Preparation of (1 a,5a,6cc)-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No.26) This compound was prepared following the procedure as in Example 7, Step c using l-bromo-3- methylbut-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.66-7.23 (m, 5H, arom.), 5.19 (t, 1H), 4.08-3.89 (dd, 2H), 3.7 (s, 1H), 3.029-2.94 (m, 4H), 2.3-2.27 (m, 3H), 1.71 - 1.11 (m, 19H ) IR (DCM): 1721cm-1 EXAMPLE 27 Preparation of (1α,5α,6α)-[3-(3-methyl-2-butenyI)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyI acetate (Compound No.27) This compound was prepared following the procedure as in Example 8, Step b using l-bromo-3- methylbut-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ-values: 7.67-7.23 (m, 5H, arom.), 5.19 (t, 1H), 4.05-3.91 (dd, 2H), 3.76 (s, 1H), 3.039-2.96 (m, 4H), 2.31-2.28 (m, 3H), 1.71-1.25 (m, 17H ) IR (DCM): 1721cm-1 EXAMPLE 28 Preparation of (2R)-(+)-(l a,5ot,6a)-N- [3-benzyl-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 28) Step a: Preparation of (2R)-(-)-2-hydroxy-2-cyclohexyl-2-phenyl acetic acid: Synthesized as per reported procedure of Paul T. Grover, et.al. J. Org. Chem. 2000, 65, 6283 - 6287 Step b: The title compound was synthesised following the procedure as in step-b of Example 2, using (2R)-(-)-2-hydroxy-2-cyclohexyl-2-phenylacetic acid instead of 2-hydroxy-2-cyclohexyl-2- phenylacetic acid. 1H-NMR (CDCl3) δ-values: 7.61-7.22 (m, 10H, arom.), 6.62 (m, 1H), 3.55 (s, 2H), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H) [α]25±3oC= +3.85° (.9846% MeOH) IR (DCM): 1651cm-1 EXAMPLE 29 Preparation of (2R)-(+)-(1α,5α,6α)-N- [3-benzyl-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)- yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.29) Step a: Preparation of (2R)-(-)-2-hydroxy-2-cyclopentyl-2-phenyl acetic acid : Synthesized as per reported procedure of Paul T. Grover, et.al. J. Org. Chem. 2000, 65, 6283 - 6287. Step b: The title compound was synthesised following the procedure in step-b of Example 3, using (2R)-(-)-2hydroxy-2-cyclopentyl-2-phenyl acetic acid instead of 2-hydroxy-2-cyclopentyl- 2-phenylacetic acid. 1H-NMR (CDCl3) δ-values: 7.61-7.26 (m, 10H, arom.), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H) IR (DCM): 1651cm-1 [α]25oC = +3.95° (.936% MeOH) EXAMPLE 30 Preparation of (2R) ( + ) - (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 30) Step a: Preparation of (2R) (-) 2-hydroxy-2-cyclohexyl-2-phenyl acetic acid : Synthesized as per reported procedure of Paul T. Grover, et.al. J. Org. Chem. 2000, 65, 6283 - 6287. Step b: The title compound was synthesized following the procedure as in Example 4, step c using (2R) (-)-2-hydroxy-2-cyclohexyl-2-phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid. 1H-NMR (CDCl3) δ-values: 7.61-7.26 (m, 10H, atom.), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H) IR (DCM): 1651cm-1 [α]25oC = +9.8° (1.09% MeOH) EXAMPLE 31 Preparation of (2R) (+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2- hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 31) Step a: Preparation of (2R) (-) 2-hydroxy-2-cyclopentyl-2-phenyl acetic acid : Synthesized as per reported procedure of Paul T. Grover, et.al. J. Org. Chem. 2000, 65, 6283 - 6287. Step b: The title compound was synthesised following the procedure as in Example 4, step c using (2R) (-)-2-hydroxy-2-cyclopentyl-2-phenylacetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid. 1H-NMR (CDCl3) δ-values: 7.67-7.2 (m, 10H, atom.), 4.06 (m, 1H), 3.93 (m, 1H), 3.74 (s, 2H), 2.94-2.89 (m, 3H), 2.33-2.3 (m,2H), 1.64-1.29 (m, 11H) IR (DCM): 1719cm-1 [ EXAMPLE 32 Preparation of (2S)-(-)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)- yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.32) Step a: Preparation of (2S) (+) 2-hydroxy-2-cyclopentyl-2-phenyl acetic acid : Synthesized as per reported procedure of Paul T. Grover, et.al. J. Org. Chem. 2000, 65, 6283 - 6287. Step b: The title compound was synthesised following the procedure in step-b of Example 3. 1H-NMR (CDCl3) δ-values: 7.62-7.25 (m, 10H. arom.), 6.45 (m, 1H), 3.58 (s, 2H), 3.07-2.92 (m, 5H), 2.35 (m, 2H), 1.77-1.24 (m, 11H ) IR (DCM): 1651cm-1 [ EXAMPLE 33 Preparation of (2S)-(-)-(1α,5α,6α)- [3-benzyl-3-azabicyclo [3.1.0] hexy l-6-(methyl)-y1] -2- hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 33) Step a: Preparation of (2S) (+) 2-hydroxy-2-cyclopentyl-2-phenyl acetic acid : Synthesized as per reported procedure of Paul T. Grover, et.al. J. Org. Chem. 2000, 65, 6283 - 6287. Step b: The title compound was synthesized following the procedure as in Example 4, Step c using 2S-(-)-2-hydroxy-2-cyclopentyl-2-phenylacetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid. 1H-NMR (CDCl3) δ-values: 7.67-7.2 (m, 10H, arom.), 4.06 (m, 1H), 3.93 (m, 1H), 3.58 (s, 2H), 2.94-2.9 (m, 3H), 2.33-2.31 (m, 2H), 1.66-1.19 (m, 11H ) IR (DCM): 1720cm-1 [α]= -14.9° (1.1% MeOH). EXAMPLE 34 Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicy clo [3.1.0] hexy l-6-(aminomethyl)-yl] -2-hydroxy-2-cyclopentyl-2-phenyl acetamide L-( + )-tartrate salt (Compound No. 34) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl- 2-phenyl acetamide (Compound No 3, 1 mmol) was dissolved in ethanol (10 ml) and a solution of L-(+)-tartaric acid (lmmol) in ethanol (5 ml) was added and stirred at 60°C for 1 hr. The reaction mixture was then concentrated by the evaporation of solvents under reduced pressure. The resulting solid was triturated with diethyl ether and diethyl ether was removed under reduced pressure to afford the title compound as a white solid. 1H-NMR (CDCl3) δ-values: 7.86 (dd, 1H, Ar-H), 7.56 (dd,2H,Ar-H), 7.33-7.16 ( m,7H,Ar-H), 5.5(bs,lH), 3.76(s,2H,benzylic), 2.97-2.77 (m, 5H), 2.50-2.45 (m, 2H), 1.50-1.22 (m, 13H) IR (KBr): 1735 cm-1, 1653cm-1 MS: [404.8]; HPLC (99% pure). EXAMPLE 35 Preparation of (2R)-(+)-(1α,5α,6α)-N- [3-benzyl-3-azabicyclo [3.1.0] hexy l-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide.L(+)-tartrate salt (Compound No. 35) 2(R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2- cyclopentyl-2-phenylacetamide(Compound No.29, lmmol) was dissolved in methanol (l0ml)and L(+)-tartaric acid was added and stirred at 60°C for lhr. The reaction mixture was concentrated under reduced pressure, the resulting solid was triturated with diethylether and it was filtered off m.p.: 95°C, starts decomposing IR(KBr): 1735cm-1,1655cm-1. HPLC:99%ee [α]25oC= +10° (1.02%MeOH) EXAMPLE 36 (2S)-(-)- (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyIacetamide.L(+)-tartrate salt(Compound No. 36) (2S)-(-)-(lα,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2- cyclopentyl-2-phenylacetamide(Compound 32,lmmol) was dissolved in ethanol (10ml) and a solution of L(+)tartaric acid (1mmol) in ethanol was added and stirred at 60°C for 1 hr. The reaction mixture was then concentrated by evaporation of solvents under reduced pressure. Dichloromethane was added to remove last traces of ethanol and to give a solid. m.p.: -56°C IR (KBr): 1739cm'1, 1653cm-1 EXAMPLE 37 Preparation of (1α,5α,6α)-N- [3-benzyl-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl] -2-hydroxy-2-cyclobutyI-2-phenylacetamide(Compound No. 37) Step a : Preparation of 2-hydroxy-2-cyclobutyl-2-phenyl acetic acid synthesised as per reported procedure of Saul B. Kadin andJosephG.Cannon.J.Org.Chem.,1962,27,240-245. Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclobutyl-2-phenylacetamide. The compound of step b was prepared by following the procedure in step c of Example 1, using 2- hydroxy-2-cyclobutyl-2-phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid. 1HNMR(CDCl3) δ-values: 7.50-7.22 (m,10H,Aromatic),6.22 (s,lH), 3.55-1.22 (m,19H). EXAMPLE 38 Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopropyl-2-phenyIacetamide (Compound No. 38) Step a:Preparation of 2-hydroxy-2-cyclopropyl-2-phenyl acetic acid. Synthesised as per reported procedure of Saul B. Kadin and Joseph G.Cannon. J.Org. Chem., 1962,27,240-245. Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2- hydroxy-2-cyclopropyl-2-phenylacetamide. The title compound was prepared by following the procedure described in step-c of Example 1, using 2-hydroxy-2-cyclopropyl phenylacetic acid instead of 2-hydroxy-2,2-diphenylacetic acid. 1H-NMRCCDCl3) δ - values: 7.63-7.23 (m,10H,aromatic), 6.11 (s,lH), 3.56 (s, 2H), 3.14-2.04 (m, 6H),1.59-1.25(m,10H). EXAMPLE 39 Preparation of (1α,5α,6α)-N-[3-(3-methyl-2-butenyl) -3-azabicyclo [3.1.0] hexy 1-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenylacetamide (Compound No. 39) The compound was prepared by using the procedure in Example 9, step b, using l-bromo-3-methyl but-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo [2,3-b]benzofuran. 1H-NMR (CDCl3) δ - values: 7.66-7.02(m,5H,Aromatic), 5.49 (t, 1H), 3.65-2.87 (m, 9H), 1.86-0.87 (m, 19H) EXAMPLE 40 Preparation of (1α,5α,6α)-[3-(3,4-methylenedioxyphenyl)methyl -3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate (Compound No. 40) Step a: Preparation of 3,4-methylenedioxy benzyl bromide. Phosphorus tribromide (0.35mmol) was added to a solution of 3,4-methylenedioxy benzyl alcohol(lmmol)in 10ml of carbon tetrachloride at room temperature. The reaction mixture was refluxed for 4hrs., cooled to room temperature and washed with sodium carbonate solution (10ml).The organic layer was dried and concentrated under reduced pressure to give the required product which was used as such for the next step. Step b: (1α,5α,6α)-[3-(3,4-methylenedioxyphenyl)methyl -3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate. The title compound was prepared using the procedure in Example 8, step b, using 3,4-methylenedioxy benzyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran. 1H-NMR (CDCl3) δ - values: 7.67-6.67(m, 8H, aromatic) ,5.94(s,2H),4.10-3.92(dd,2H), 3.71(s,lH),3.47(s,2H),2.91-2.87(m,2H),2.30-2.27(m,3H),1.64-1.12(m, 13H) IR(DCM): 1720cm-1 EXAMPLE 41 Preparation of (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl )-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate. L(+)-tartrate salt (Compound No. 41). The compound was prepared by using the procedure in Example 34 using (1α,5α,6α)-[3-(2-(3,4- methylenedioxyphenyl)ethyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2- phenyl acetate in place of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)- yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide. m.p.:88-91°C IR(KBr): 1725cm-1,1608cm-1. EXAMPLE 42 Preparation of (1α,5α,6α)- [3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-y 1]-2-hydroxy-2,2 diphenyl acetate. L(+)-tartrate salt (Compound No. 42) The compound was prepared by using the method of Example 34 using (la,5a,6cc)-[3-benzyl-3- azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2 diphenyl acetate instead of (1α,5α,6α)-N- [3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2- phenylacetamide. m.p.: 53-54°C IR(DCM):1730cm-1. EXAMPLE 43 Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate .L(+)-tartrate salt(Compound No. 43) The compound was prepared by using the method of Example 34 using(lα,5α,6α)-[3-benzyl-3- azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl- 2-phenylacetamide. m.p.: 54°C IR(DCM): 1725cm-1. EXAMPLE 44 Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate .L(+)-tartrate salt (Compound No. 44) The compound was prepared by using the method of Example 34 using (1α,5α,6α)-[3-benzyl-3- azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl- 2-phenylacetamide. m.p.: 55°C IR(DCM): 1726cm-1. EXAMPLE 45 Preparation of (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 45) This compound was prepared following the procedure as in Example 9, Step b using 3- chloromethylpyridine hydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b] benzofuran. 1H-NMR (CDCl3) δ- values: 8.49-8.47 (m, 2H, aromatic); 7.62-7.21 (m, 7H, Aromatic); 6.66 (bs, 1H), 3.56 (s, 2H), 3.07-2.30 (m, 8H), 1.76-1.21 (m, 12H). EXAMPLE 46 Preparation of (1α,5α,6α)-N- [3-(4-pyridylmethyl)-3-azabicyclo [3.1.0] hexy 1-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenylacetamide (Compound No. 46) This compound was prepared following the procedure as in Example 9, Step b using 4- chloromethylpyridine hydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b] benzofuran. m.pt.: 61-62°C 1H-NMR (CDCl3) δ- values: 8.52-8.50 (m, 2H, aromatic); 7.62-7.18 (m, 7H, Aromatic); 6.71 (bs, 1H), 3.56 (s, 2H), 3.08-2.30 (m, 7H), 1.70-1.17 (m, 13H). IR(KBr): 1658cm'1 EXAMPLE 47 Preparation of (1α,5α,6α)-N- [3-(2-pyridylmethyl)-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyIacetamide (Compound No. 47) This compound was prepared following the procedure as in Example 10, Step b using 2-chloromethylpyridine hydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b] benzofuran. m.pt.: 62-63°C 1H-NMR (CDCl3) δ- values: 8.52-8.50 (m, 2H, aromatic); 7.65-7.12 (m, 7H, Aromatic); 6.68 (bs, 1H), 3.73 (s, 2H), 3.00-2.36 (m, 8H), 1.76-1.16 (m, 12H). IR(KBr): 1654cm-1 EXAMPLE 48 Preparation of (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexy 1-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyIacetamide (Compound No. 48) This compound was prepared following the procedure as in Example-10, Step b using 4- chloromethyl pyridinehydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b] benzofuran. 1H-NMR (CDCl3) δ-values: 8.51-8.49 (m, 2H, Aromatic), 7.63-7.18 (m, 7H, aromatic), 6.64 (bs, 1H), 3.56 (s, 2H) EXAMPLE 49 Preparation of (1α,5α,6α)-N- [3-(3-pyridylmethyl)-3-azabicyclo [3.1.0] hexy 1-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide (Compound No. 49) The compound obtained as in Example-1 was debenzylated and then N-alkylated as given below: Step-a: Preparation of (1α,5α,6α)-N-[3-azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide: This was synthesized using the same procedure as per Example 8, Step-a using (la,5a,6oc)-N-3-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide instead of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate 1H-NMR (CDCl3) δ-values: 7.44-7.25 (m, 10H, Aromatic), 3.26-2.27 (m, 7H), 1.40-1.27 (m, 2H) Step-b: To a solution of compound (1α,5α,6α)-N-[3-azabicyclo[3.1.0]-hexyl-6-(aminomethyl)- yl]-2-hydroxy-2,2-diphenylaceticamide (0.322g, lmmol) in dimethyl formamide (5 ml) was added 3-chloromethylpyridine hydrochloride (0.246, 1.5 mmol) and potassium carbonate (2 mmol, 0.276g), potassium iodide (1 mmol, 0.166 g) ) and 5-(2-bromoethyl)-2,3- dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2mmol). The reaction mixture was stirred at RT overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100- 200 mesh) eluting the compound with 20:80 ethyl acetate : hexane. 1H-NMR (CDCl3) δ-values: 8.51-8.50 (m, 2H, aromatic), 7.64-7.25 (m, 12H, aromatic), 6.47 (bs, 1H), 3.61 (s, 2H), 3.23-3.18 (m, 2H), 2.96-2.88 (m, 2H), 2.10-2.03 (m, 2H), 1.48-1.14 (m, 3H). IR(DCM): 1646cm-1 EXAMPLE 50 Preparation of (1α,5α,6α)-N- [3-(4-pyridyImethyl)-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No. 50) This compound was prepared following the procedure as in Example 49, Step b using 4- chloromethyl pyridine hydrochloride instead of 3-chloromethyl pyridine hydrochloride. 1H-NMR (CDCl3) δ-values: 8.48-8.46 (m, 2H, Aromatic), 7.66-7.18 (m, 12H, Aromatic), 6.52 (bs, 1H), 3.57 (s, 2H), 3.20-3.16 (m, 2H), 2.96-2.93 (m, 2H), 2.35-2.30 (m, 2H), 1.60-1.25 (m, 3H). IR(KBr): 1658cm-1 EXAMPLE 51 Preparation of (1α,5α,6α)-N- [3-(2-pyridylmethyl)-3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No. 51) A solution of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide (0.322g, 1 mmol), 2-pyridine carboxaldehyde (0.256g, 2.4 mmol), sodium triacetoxy borohydride (0.678g, 3.2 mmol) and acetic acid (0.228g, 3.8 mmols) in tetrahydrofuran (25 ml) was stirred for 4 days. The reaction mixture was poured into saturated sodium bicarbonate solution and extracted with ethyl acetate. The organic layer was washed with water, dried over sodium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography (100x200 mesh, size silicagel) using 80:20 ethyl acetate : dichloromethane. 1H-NMR (CDCl3) δ-values: 8.53-8.52 (m, 1H, Aromatic), 7.67-7.14 (m, 13H, Aromatic), 6.39 (bs, 1H), 3.74 (s, 2H), 3.20-3.16 (m, 2H), 3.01-2.98 (m, 2H), 2.15-2.02 (m, 3H), 1.33-1.19 (m, 2H) IR(KBr): 1658cm-1 EXAMPLE 52 Preparation of (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo [3.1.0] hexy 1-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 52) This compound was synthesized following the procedure of Example 51 using (lα,5α,6α)-N-[3- azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cycopentyl-2-phenyl acetamide instead of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide. 1H-NMR (CDCl3) δ-values: 8.52 (m, 1H, Aromatic), 7.67-7.16 (m, 8H, Aromatic), 6.47 (bs, 1H), 3.74 (s, 2H), 3.08-2.02 (m, 9H), 1.66-0.88 (m, 10H) IR(KBr): 1644 cm-1 EXAMPLE 53 Preparation of (lα,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0] hexy 1-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 53) This compound was synthesized using the procedure of Example 10, Step b but using 3-chloromethylpyridine hydrochloride intead of 5-(2-bromoethyl)-2,3-dihydrobenzo [2,3-b) benzofuran. 1H-NMR (CDCl3) δ-values: 8.53-8.51 (m, 2H, Aromatic), 7.63-7.18 (m, 7H, Aromatic), 6.5 (bs, 1H), 3.57 (s, 2H), 3.12-3.91 (m, 6H), 2.33-2.31 (m, 2H), 1.40-1.17 (m, 10H) IR(KBr): 1642 cm-1 EXAMPLE 54 Preparation of (1α,5α,6α)-N-[3-(3~methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 54) This compound was synthesized by following the procedure of Example 10, Step b but using 1-bromo-3-methyl-but-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo [2,3-b] benzofuran. 1H-NMR (CDCl3) δ-values: 7.61-7.26 (m, 5H, Aromatic), 6.43 (bs, 1H), 5.20 (t, 1H), 3.07-2.98 (m, 7H), 2.33-2.30 (m, 2H), 1.76-0.92 (m, 17H) EXAMPLE 55 Preparation of (1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (Compound No. 55) This compound was synthesized by following the procedure of Example 51 but using 3,4-methylenedioxybenzaldehyde instead of 2-pyridine carboxaldehyde, and (1α,5α,6α)-N-[3-azabicyclo [3.1.0] hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide instead of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide. m.p.: 148-150°C 1H-NMR (CDCl3) δ-values: 7.61-6.66 (m, 8H, Aromatic), 6.42 (bs, 1H), 5.93 (s, 2H), 3.46 (s, 2H), 3.19-2.88 (m, 6H), 2.29-2.27 (m, 2H), 1.71-1.22 (m, 11H) IR(KBr): 1652 cm-1 EXAMPLE 56 Preparation of (1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexy1-2-phenyl acetamide (Compound No. 56) This compound was synthesized by following the procedure of Example 51 but using (la,5cc,6a)-N- [3 -azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenylacetamide instead of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide and 3,4-methylenedioxybenzaldehyde instead of 2-pyridine carboxaldehyde. m.p.: 130-133°C 1H-NMR (CDCl3) δ-values: 7.61-6.68 (m, 8H) δ.93 (s, 2H), 3.45 (s, 2H), 2.92-2.84 (m, 5H), 2.28-2.26 (m, 2H), 1.34-1.17 (m, 13H) IR(KBr): 1651cm-1 EXAMPLE 57 Preparation of (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyI acetate. L(+) tartrate salt (Compound No. 57) This compound was synthesized by following the procedure of Example 34 but using (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. m.p.: 87-89°C HPLC: 94.6% EXAMPLE 58 Preparation of (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo [3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate. L(+) tartrate salt (Compound No. 58) This compound was synthesized by following the procedure of Example 34 but using (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3 -azabicyclo [3.1.0]hexyl-6-(methyl)-yl] -2-hydroxy-2-cyclohexyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. m.p.: 76°C (starts decomposing) HPLC: 97.48% EXAMPLE 59 Preparation of (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate. L(+) tartrate salt (Compound No. 59) This compound was synthesized following the procedure of Example 34 but using (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0] hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. m.p.: 78°C (starts decomposing) HPLC :94.2% EXAMPLE-60 Preparation of (lα,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide .hydrochloride salt (Compound No. 60) This compound was synthesized by the following procedure: Ethereal hydrochloric acid (10 ml) was added to a solution of compound 3 (1 mmol) in ethanol (5 ml). The reaction mixture was stirred at room temperature and then concentrated under reduced pressure. HPLC :96.39% EXAMPLE 61 Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide . L(-) malic acid salt (Compound No. 61) This compound was synthesised by following the procedure of Example 34 but using L(-) malic acid instead of L-(+) tartaric acid HPLC : 98.28% EXAMPLE 62 Preparation of (lα,5α,6α)-N-[3-benzyl-3-azabicydo[3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. Maleate salt (Compound No. 62) This compound was synthesized by following the procedure of Example 34 but using malic acid instead of L-(+) tartaric acid HPLC : 98.37% Biological Activity Radioligand Binding Assays: The affinity of test compounds for M2 and M3 muscarinic receptor subtypes was determined by [3H]-N-methylscopolamine binding studies using rat heart and submandibular gland respectively as described by Moriya et al., (Life Sci, 1999,64(25):2351-2358) with minor modifications. Membrane preparation: Submandibular glands and heart were isolated and placed in ice cold homogenising buffer (HEPES 20mM, 10mM EDTA, pH 7.4) immediately after sacrifice. The tissues were homogenised in 10 volumes of homogenising buffer and the homogenate was filtered through two layers of wet gauze and filtrate was centrifuged at 500g for 10min. The supernatant was subsequently centrifuged at 40,000g for 20 min. The pellet thus obtained was resuspended in same volume of assay buffer (HEPES 20 mM, EDTA 5mM, pH 7.4) and were stored at -70°C until the time of assay. Ligand binding assay: The compounds were dissolved and diluted in DMSO. The membrane homogenates (150-250 µg protein) were incubated in 250 ul of assay buffer (HEPES 20 mM, pH 7.4) at 24-25°C for 3h. Non-specific binding was determined in the presence of 1 uM atropine . The incubation was terminated by vacuum filtration over GF/B fiber filters(Wallac). The filters were then washed with ice cold 50mM Tris HC1 buffer (pH 7.4). The filter mats were dried and bound radioactivity retained on filters was counted. The IC50 & Kd were estimated by using the non-linear curve fitting program using G Pad Prism software. The value of inhibition constant Ki was calculated from competitive binding studies by using Cheng & Prusoff equation (Biochem Pharmacol, 1973,22: 3099-3108), Ki = IC50 /(1+L/Kd), where L is the concentration of [3H]NMS used in the particular experiment. Functional Experiments using isolated rat bladder: Methodology: Animals were euthanized by overdose of urethane and whole bladder was isolated and removed rapidly and placed in ice cold Tyrode buffer with the following composition (mMol/L) NaCl 137; KC1 2.7; CaCl2 1.8; MgCl2 0.1; NaHC03 11.9; NaH2PO4 0.4; Glucose 5.55 and continuously gassed with 95% 02 and 5 % CO2. The bladder was cut into longitudinal strips (3 mm wide and 5-6 mm long) and mounted in 10 ml organ baths at 30° C, with one end connected to the base of the tissue holder and the other end connected to a polygraph through a force displacement transducer. Each tissue was maintained at a constant basal tension of 2 g and allowed to equilibrate for 1 hour during which the PSS was changed every 15 min. At the end of equilibration period the stabilization of the tissue contractile response was assessed with 1µmol/L of Carbachol consecutively for 2-3 times. Subsequently a cumulative concentration response curve to carbachol (10-9 mol/L to 3 X 10-5 mol/L) was obtained. After several washes, once the baseline was achieved, cumulative concentration response curve was obtained in presence of NCE (NCE added 20 min. prior to the second CRC). The contractile results were expressed as % of control E max. ED50 values were calculated by fitting a non-linear regression curve (Graph Pad Prism). pKB values were calculated by the formula pKB = - log [ (molar concentration of antagonist/ (dose ratio-1))] where, dose ratio = ED50 in the presence of antagonist/ED50 in the absence of antagonist. In vivo experiments using anaesthetized rabbit Methodology Male rabbits were anaesthetized with urethane 1.5g/kg intravenously. Trachea was cannulated to maintain the patency of airway. Femoral vein and femoral arteries of both sides were cannulated for the administration of vehicle or drug substances for the measurement of BP and administration of carbachol intra-arterially respectively. Polyethylene tubing was introduced into the bladder through the urethra and tied at the neck of the bladder. The other end of the catheter was connected to the Grass polygraph through a Statham pressure transducer. The bladder was filled with warm (37°C) saline. Both the ureters were ligated and cut proximally to drain the urine coming from kidneys. A stabilization period of 30-60 was allowed for stabilization of parameters from surgical procedures. Salivary response was assessed by measuring the weight of a preweighted cotton gauze kept for 2 minutes in the buccal cavity immediately after the carbachol challenge. At the end of stabilization period 2 control responses to carbachol (1.5µg/kg intra-arterial) on bladder pressure and salivation were obtained and this response was considered as 100%. Subsequently, the effect of increasing dose of NCE (ranging from 3 µg/kg to 1mg/kg) or vehicle (i.v., 15 min before carbachol challenge) was examined. The change in bladder pressure and salivation were expressed as % change from pretreatment control averages. The ID50 values for salivation and bladder pressure inhibition were calculated using Graph Pad Prism software, by fitting the values at dose into non-linear regression curve. Oxybutynin and Tolterodine were used as standards for comparison. The bladder selectivity to salivation was calculated by using following formula and expressed as fold of selectivity of oxybutinin in the same model. ID50 Salivary response ID50 Bladder pressure The results of the in-vitro and in-vivo tests are listed in Tables II and III. In -Vitro tests Table-ll (Table Removed) While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention. WE CLAIM: 1. 3,6-disubstituted azabicyclo[3.1 .0]hexane compounds having the structure of Formula I: (Formula Removed) wherein Ar represents an aryl or a heteroaryl ring having 1-2 hetero atoms selected from the group consisting of oxygen, sulphur and nitrogen atoms, the aryl or heteroaryl rings may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C1-C4), lower perhalo alkyl (C1-C4), cyano, hydroxy, nitro, lower alkoxy (C1-C4), lower perhalo alkoxy (C1-C4), unsubstituted amino, N-lower alkyl (C1-C4) amino or N-lower alkyl(C1-C4) amino carbonyl; R1 represents a hydrogen, hydroxy, hydroxy methyl, amino, alkoxy, carbamoyl or halogen (e.g. fluorine, chlorine, bromine and iodine); R2 represents alkyl, C3-C7 cycloalkyl ring, a C3-C7 cyclo alkenyl ring, an aryl or a heteroaryl ring having 1 to 2 hetero atoms selected from a group consisting of oxygen, sulphur and nitrogen atoms; the aryl or a heteroaryl ring may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C1-C4), lower perhalo alkyl (C1- C4), cyano, hydroxy, nitro, lower alkoxycarbonyl, halogen, lower alkoxy (C1-C4), lower perhalo alkoxy (C1-C4), unsubstituted amino, N-lower alkylamino (C1-C4), N-lower alkylamino carbonyl (C1-C4); W represents (CH2)p, where p represents 0 to 1; X represents an oxygen, sulphur, nitrogen or no atom; Y represents CHR5CO wherein R5 represents hydrogen or methyl or (CH2)q wherein q represents 0 to 4; Z represents oxygen, sulphur, NR10, wherein R10 represents hydrogen, C1-6 alkyl Q represents (CH2)n wherein n represents 0 to 4, or CHR8 wherein R8 represents H, OH, C1-6, alkyl, alkenyl alkoxy or CH2CHR9 wherein R9 represents H, OH , lower alkyl (C1-C4) or lower alkoxy (C1-C4); R6 and R7 are independently selected from COOH, H, CH3, CONH2, NH2, CH2NH2; R4 represents C1-C15 saturated or unsaturated aliphatic hydrocarbon groups in which any 1 to 6 hydrogen atoms may be substituted with the group independently selected from halogen. arylalkyl, arylalkenyl, heteroarylalkyl or heteroarylalkenyl having 1 to 2 hetero atoms selected from a group consisting of nitrogen, oxygen and sulphur atoms with option that any 1 to 3 hydrogen atoms on the ring in said arylalkyl, arylalkenyl, hetero arylalkenyl group may be substituted with lower alkyl(C1-C4), lower perhalo alkyl (C1-C4), cyano, hydroxyl, nitro, lower alkoxycarbonyl, halogen, lower alkoxy (C1-C4), lower perhaloalkoxy (C1-C4), unsubstituted amino, N-lower alkyl(C1-C4) amino, N-lower alkyl (C1-C4)amino carbonyl. 2. The compound as claimed in claim 1 having the structure of Formula II (Formula I when R6 and R7 = H), wherein Ar, R1, R2, W, X, Y, Z, Q and R4 are as defined for Formula I. (Formula Removed) 3. The compound as claimed in claim 1 having the structure of Formula III (Formula I wherein W is (CH2)p where p = 0, X is no atom and Y is (CH2)q where q=0, R6 = H, R7 = H), wherein Ar, R1, R2, Z, Q and R4 are as defined for Formula I. (Formula Removed) 4. The compound as claimed in claim 1 having the structure of Formula IV [Formula I wherein W is (CH2)p where p = 0, X is no atom and Y is (CH2)q where q=0, Rg = H, R7 = H and R2 = ,wherein Ar, R1, Z, Q and R4 are as defined for Formula I, and r is 1 to 4. (Formula Removed) 5. The compound as claimed in claim 1 having the structure of Formula V (Formula-I wherein W is (CH2)p where p = 0, X is no atom and Y is (CH2)q where q=0, R6 = H, R7 = H, R2 = , R1 is hydroxy, Ar is phenyl), wherein R4 , Z and Q are the same as defined for Formula I, and s represents 1 to 2. (Formula Removed) 6. A compound as claimed in claim 1 selected form the group consisting of: (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide.(Compound No. 1) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 2) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.(Compound No. 3) (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2-diphenyl acetate.(Compound No. 4) (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cycIohexyl-2-phenyl acetate.(Compound No. 5) (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 6) (1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate.(Compound No. 7) (1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyClopentyl-2-phenyl acetate.(Compound No. 8) (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 9) (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.(Compound No. 10) (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 11) (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate.(Compound No. 12) (1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-. ,(aminomethyl).-yl]-2-hydrnxy-2-cyclopentyl-2-nhenyl acetamide.(Compound No 13) (1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 14) (1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 15) (1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.(Compound No. 16) (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate.(Compound No. 17) (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 18) (1α,5α,6α)-[3-(l-pbeny!ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 19) (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate.(Compound No. 20) (1α,5α,6α)-N-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 21) (1α,5α,6α)-N-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyI)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.(Compound No. 22) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide.(Compound No. 23) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-( 1-aminoethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 24) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(l-aminoethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.(Compound No. 25) (1α,5α,6α)-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate.(Compound No. 26) (1α,5α,6α)-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 27) (2R)-(+)- (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 28) (2R)-(+)- (1 a,5a,6a)-N- [3 -benzyl-3 -azabicyclo [3.1.0]hexyl-6-(aminomethyl)-yl] -2-hydroxy-2-cyclopentyI-2-phenyl acetamide.(Compound No. 29) (2R)(+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate.(Compound No. 30) (2R) (+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 31) (2S)-(-)- (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.(Compound No. 32) (2S)-(-)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 33) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-.cyclopentyl-2-phenyl acetamide L-(+)-tartrate salt,(Compound No. 34) (2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide. L-( + )-tartrate salt.(Compound No. 35) (2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. L-( + )-tartrate salt.(Compound No. 36) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclobutyl-2-phenyl acetamide.(Compound No. 37) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopropyl-2-phenyl acetamide.(Compound No. 38) (1α,5α,6α)-N-[ 3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.(Compound No. 39) (1α,5α,6α)-f 3-(3,4- methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate.(Compound No. 40) (1α,5α,6α)- [3 -(2-(3,4-methylenedioxyphenyl)ethyl)-3 -azabicyclo [3.1.0]hexyl-6-(methyl)-yl] -2-hydroxy-2-cyclopentyl-2-phenyl acetate. L-(+)-tartrate saIt.(Compound No. 41) (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2 diphenyl acetate L(+)-tartrate salt .(Compound No. 42) (1α,5α,6α)- [3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate L(+)-tartrate salt.(Compound No. 43) (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate L(+)-tartrate salt. (Compound No. 44) (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compoimd No. 45) (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No.46) (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No.47) (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.48) (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No.49) (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No.50) (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound 51) (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.52) (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.53) (1α,5α,6α)-N-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.54) (1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yI]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No.55) (1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound 56) (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate L(+) tartrate salt(Compound 57) (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate. L(+) tartrate salt(Compound 58) (1α,5α,6α)-[3-(l-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate. L(+) tartrate salt(Compound 59) (1α,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide hydrochloride salt (Compound No. 60) (lα,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide . L(-) malic acid salt (Compound No. 61) (lα,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. maleate salt (Compound No. 62) 7. A process of preparing a compound of Formula I, (Formula Removed) (a) condensing a compound of Formula-VII with a compound of Formula VI (Formula Removed) wherein the reaction of compound of Formula VII with compound of Formula VI to give a compound of Formula VII is carried out in the presence of condensing agent selected from the group consisting of l-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride (EDC) and l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in the presence of solvents selected from group consisting of N,N-dimethylformamide, dimethylsulfoxide, toluene and xylene at a temperature ranging from 0-140°C. (Formula Removed) (b) deprotecting the compound of Formula VIII in the presence of a deprotecting agent selected from a group consisting of palladium on carbon, trifluoroacetic acid (TFA) and hydrochloric acid to give an unprotected intermediate of Formula IX (Formula Removed) (c) the intermediate of Formula IX is N-alkylated or benzyiated with a suitable alkylating or benzylating agent L-R4 (wherein L is any leaving group and R4 is the same as defined earlier) to give a compound of Formula I.

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