Indian Patents. 192890:A PROCESS FOR THE PREPARATION OF A 4,5-DIAMINO SHIKIMIC ACID DERIVATIVE

Title of Invention	A PROCESS FOR THE PREPARATION OF A 4,5-DIAMINO SHIKIMIC ACID DERIVATIVE
Abstract	The invention provides a multistep synthesis for the preparation of 4,5-diamino shikimic acid derivatives of formula starting from furan. Abstract The invention provides a multistep synthesis for the preparation of 4,5-diamino shikimic 5 acid derivatives of formula starting from furan. 10 4,5-Diamino shikimic acid derivatives are potent inhibitors of viral neuraminidase.

Full Text	The present invention relates to a multi step process for the preparation of 4,5-diamino Chichimec acid derivatives, especially for the preparation of (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxylic acid ethyl ester and its pharmaceutically acceptable addition salts starting from furan as well as new specific intermediates. 4,5-diamino shikimic acid derivatives, especially the (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxylic acid ethyl ester and its pharmaceutically acceptable addition salts are potent inhibitors of viral neuraminidase ( J.C.Rohloff et al., J.Org.Chem., 1998, 63, 4545-4550; WO 98/07685). A multi step synthesis of (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-1-carboxylic acid ethyl ester from (-)-quince acid or (-)-Chichimec acid is described in (J.C.Rohloff et al, loc.cit.). Both (-)-quinic acid and (-)-shikimic acid are starting compounds which are rather expensive and hardly accessible in technical quantities. A multi step synthesis capable to run on a technical scale should therefore preferably be based on starting compounds which are more attractive in price and available in technical quantities. Object of the present invention therefore is to provide such a new access to the 4,5-diamino shikimic acid derivatives mentioned above in good yields and excellent quality. It was found that with the synthesis according to claim 1 this object could surprisingly be achieved. The present invention therefore relates to a process for the preparation of a 4,5-diamino shikimic acid derivative of formula RAU/20.12.2000 and pharmaceutically acceptable addition salts thereof wherein R1 is an optionally substituted alkyl group, R is an alkyl group and R and R , independent of each other are H or a substation of an amino group, with the proviso that not both R3 and R4 are H, a process which is characterized in that in step b) the 2R-exo isomer of the bicycle compound of formula (III) is separated, in step c) this 2R-exo isomer of the biked compound of formula (III) is reacted with an azide to form an ranitidine of formula wherein R" is as above and wherein R^ is the residue of an azide the step d) wherein R^ and R^ are as above , in step e) a constituent R* is introduced in the free OH-position and the ranitidine ring is opened to give a cyclohexene derivative of formula wherein R1, R2 and R5 are as above and R6 is a subsistent of an OH group, in step f) R5 is removed to yield a 4-amino cyclohexene derivative of formula wherein R1, R2 and R6 are as above this 4-amino cyclohexene derivative of formula (VII) is finally processed to the 4,5-diamino shikimic acid derivatives of formula (I) by step g) comprising either gn transformation of the 4-amino cyclohexene derivative of formula (VII) into an ranitidine of formula wherein R' and R' are as above, gi2 formation of the azide of formula gi3 reduction and, if necessary the formation of the pharmaceutically acceptable addition salt, wherein R1 and R" are as above and R' and R^, independent of each other are H or a substituent of an amino group, with the proviso that not both R7 and R8 are H g22 vacillation of the amino group in position 4 and g23 releasing the amino group in position 5 and, if necessary the formation of the pharmaceutically acceptable addition salt. The term alkyl in R'1 has the meaning of a straight chained or branched alkyl group of 1 to 20 C-atoms, expediently of 1 to 12 C-atoms. Examples of such alkyl groups are methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, tert.-butyl, pentyl and its isomers, hexyl and its isomers, hotly and its isomers, octyl and its isomers, nonyl and its isomers, dactyl and its isomers, unequal and its isomers and dodecyl and its isomers. > This alkyl group can be substituted with one or more substituents as defined in e.g. WO 98/07685. Suitable substituents are alkyl of 1 to 20 C-atoms (as defined above), alkenyl with 2 to 20 C-atoms, cycloalkyl with 3 to 6 C-atoms, hydroxy, alloys with 1 to 20 C-atoms, alkoxycarbonyl with 1 to 20 C-atoms, F, CI, Br, and J. Preferred meaning forR'isl-ethylpropyl. R" is a straight chained or branched alkyl group of 1 to 12 C-atoms, expediently of 1 to 6 C-atoms, as exemplified above. Preferred meaning for R2 is ethyl. The substituent R6 refers to any substitute for OH groups conventionally used and kno\s'n in the art. They are described e.g. in "Compendium of Organic Methods" or in "Advanced Organic Chemistry", ed. March J., John Wiley & Sons, New York, 1992, 353-357. Preferably R6 is a sulfonyl group, more preferably optionally substituted aryl sulfonyl or alkyl sulfonyl such as p-toluenesulfonyl, p-nitrobenzenesulfonyl, p-bromo benzenesulfonyl, trifluoromethanesulfonyl or methanesulfonyl, most preferably methanesulfonyl. The term substituent of an amino group in R" and R** or R' and R^ refers to any substituent conventionally used and known in the art. They are described e.g. in "Protective Groups in Organic Chemistry", Theodora W. Greene et al., John Wiley 8 Preferred substituents for R3 and R4 are alkanoyl groups, more preferably lower alkanoyl with 1 to 6 C-atoms such as humanely, pentanoyl, butanoyl (butyryl), propanoyl (propionyl), ethanoyl (acetyl) and methanoyl (formal). Preferred alkanoyl group and therefore preferred meaning for R' is acetyl and for R^ is H. Preferred substituent for R7 and R8 is straight chained or branched alkenyl with 2 to 6 C-atoms, preferably ally or an analog thereof. Suitable analog of alkyl is an alkyl group which is substituted on the a-, j8-or y-carbon by one lower alkyl, lower alkenyl, lower alkynes or aryl group. Suitable examples are e.g. 2-methylallyl, 3,3-dimethylallyl, 2-phenylallyl, or 3- methallyl. Most preferred meaning for R^ is alkyl and for R* is H. .' Preferred 4,5-diamino shikimic acid derivative of formula (I) is the (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxylic acid ethyl ester and the ethyl (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxyl ate Phosphate (1:1) Step a) Step a) comprises a Diels-Alder reaction of furan with an acrylic acid derivative. Diels-Alder reactions per se are known to the skilled in the art (see e.g. Tetrahedron Letters, 23, 1982, 5299-5302). The present conversion can therefore be performed following the methods and conditions described in the art. Suitable derivatives of an acrylic acid are the esters and the amides, preferably the esters, more preferably lower alkyl esters of acrylic acid. Usually this type of reaction needs the presence of Lewis acids. Suitable Lewis acids are magnesium halogenides such as magnesium chloride, magnesium bromide or magnesium iodide or zinc halogenides such as zinc chloride, zinc bromide or zinc iodide. Preferred Lewis acid was found to be zinc chloride. As a rule catalytic amounts of the Lewis acid are applied, however it was surprisingly found that stoechiometric amounts or even an excess of the Lewis acid, preferably of zinc chloride within a reasonable time lead to an excellent exo/endo ratio of the bicycle compound of formula (III) of up to 9:1. Preferably stoechiometric amounts of zinc chloride are used. !]convenient solvent for step a) is the reactant acrylic acid derivative itself, used m an excess of up to 50%. It is however always possible to add an inert solvent. The reaction temperature can be chosen in the range of 20°C to 70°C. \fter termination of the reaction work up can take place using methods well known to the skilled in the art. Step b) Step b) comprises separation of the 2R-exo isomer of the bicycio compound of formula (III), preferably of the optical pure 2R-exo isomer of the bicycio compound of formula (III). Step a) provides the racemate of an exo/endo mixture of the bicycio compound, wherein the exo form in the mixture is enriched up to a ratio of 9:1. As a principle separation of endo and exo forms of a compound can take place by taking advantage of the different physical properties of these forms such as different boiling points. Separation of each of the two optical isomers however have to take place either by classical racemate resolution techniques or by a stereo selective methods, e.g. by an enzymatic approach. The desired 2R-exo form of the bicycio compound can accordingly be gained by physical separation of the exo and endo form e.g. by distillation, by converting the exo-ester into the respective acid and finally by a subsequent racemate resolution using classical resolving agents such as (-)-ephedrine hydrochloride or S-(-)-l-phenyl ethylamine. Preferably, however the exo/endo mixture of step a) is treated with an enzyme which is capable to hydrolyze specifically the 2S-exo isomer only and which is leaving the 2R-exo isomer untouched. It was found that ideally lipases of the EC class 3.1.1.3 or lipoprotein lipases of the EC class 3.1.1.34 are used. Suitable representatives of tl?ese classes are lipases of the genus Candida, more preferably of Candida antarctica. Such lipases are commercially available. Most preferred enzyme is the B-form of lipase Candida antarctica vv^hich is offered under the tradename Chirazyme©L2 from Roche Diagnostics or as Lipase SP-525 from Novo Nordisk. As a common alternative immobilized enzymes maybe used. The reaction is usually carried out in a monophasic or biphasic aqueous system, preferably in a biphasic system with an polar solvent as co-solvent. Suitable co-solvents are alkenes, cycloalkanes or cycloalkenes. Cyclohexane, cyclohexene and octane was found to be the most preferred co-solvent. The common aqueous buffer solutions known to be used for biochemical conversions are used in order to maintain the pH in the range of 6.5 to 8.0. Suitably sodium or potassium phosphate buffers or borate buffers can be applied. Such a buffer solution can additionally contain NaCl or KCl in a concentration of 50 to 300 mM. A preferred buffering system could e.g. contain 0.1 M KCl and 5 mM potassium borate pH 7.5. The ratio organic solvent / aqueous phase is in the range of 1:10 to 3:2. Overall substrate concentration is expediently chosen in the range of 5 to 20 wt.%, preferably in the range of 5 to 10 wt.%. Suitable reaction temperature is 0°C to 25°C, preferably close to freezing temperature of the reaction mixture. The resulting 2S-exo acid is preferably neutralized by the controlled addition of a base such as NaOH or KOH, whereby the unleaded 2R-exo ester together with the endo isomers remains in the organic phase and is separated by way of extraction with a common organic solvent. Separation of the 2R-exo ester from the endo isomers can take place by a distillation in vacuous, preferably at a temperature in the range of 70°C and 100°C and a pressure of 0.1 mbar to 10 mbar. Step c) Step c) comprises the reaction of the 2R-exo isomer of the bicyclo compound of formula (III) with an azide. Suitable azides are found to be these which are capable to form an aziridine ring in endo-position to the bridgehead of the bicyclic system. Unexpectedly phosphoryl azides of the formula wherein R is dialkoxyphosphoryl or diaryloxyphosphoryl, preferably diaryloxyphosphoryl, most preferably diphenyloxyphosphoryl fulfilled this task. Most preferred phosphoryl azide is the diphenyloxy-phosphoryl azide (DPPA). The preference of DPPA is mainly based on its availability in technical quantities and its lower toxicity compared to the dialkoxyphosphoryl azides. The phosphoryl azide is conveniently added in an amount of 0.8 equivalents to 1.0 equivalents relating to the 2R-exo bicyclo compound gained in step b). Preferably stoechiometric amounts of the phosphoryl azide are added. The choice of a solvent is not critical as long as it is inert to the reactants. Toluene or dioxins were found to be suitable solvents. The reaction temperature is chosen expediently between 40°C and 80°C. In case R has the preferred meaning of diaryloxy phosphoryl, a trarliesterification can be performed to transform the diaryloxy phosphoryl group into a dialkoxy phosphoryl group. Accordingly the azide residue R5 is dialkoxy-phosphoryl, preferably di-(Ci.6) alkoxy-phosphoryl, most preferably dithery-phosphoryl. Transesterifications are methods known to the skilled in the art, but as a rule take place in the presence of an alcoholate in the corresponding alcohol. Within the most preferred method transesterification takes place in the presence of sodium ethanol ate in ethanol. Step d) Step d) comprises eliminative ring opening of the aziridine of formula (IV) to the cyclohexene aziridine derivative of formula (V). This reaction is performed in the presence of a strong organic base. Expediently alkali-bis -(trialkylsilyl) amides, preferably alkali-bis-(trimethylsilyl) amides such as lithium bis-(trimethylsilyl) amide, sodium-bis-(trimethylsilyl) amide or potassium-bis-(trimethylsilyl) amide are used. Usually the strong organic base is used in amount of 1.0 equivalent to 2.5 equivalents relating to one equivalent of the aziridine of formula (V). The choice of a solvent also for this step is not critical as long as it is inert to the reactants. Dioxins or tetrahydrofuran were found to be suitable solvents. The reaction temperature is expediently maintained in the range of-80°C to 0°C, preferably in the range of-80°C to -20°C. The cyclohexene aziridine of formula (V) can be isolated after an acidic work up applying methods known to the skilled in the art. Step e) Step e) comprises introduction of a substituent R^ in the free OH-position and ring opening of the aziridine ring to give cyclohexene derivatives of formula (VI). The sequence, however can also be changed such that ring opening is first and introduction of substituent R^ in the free OH-position comes second. Preferably however is to first introduce substituent R into the free OH-position and to perform ring opening as second step. Compounds and methods for effecting such a substitution are well known in the art and described e.g. in "Compendium of Organic Methods" or in "Advanced Organic Chemistry", ed. March J., John Wiley & Sons, New York, 1992, 353-357. It was found that the hydroxy group is preferably transformed into a sulfonic acid ester, R therefore preferably is a sulfonyl group, more preferably optionally substituted aryl sulfonyl or alkyl sulfonyl such as p-toluenesulfonyl, p-nitrobenzenesulfonyl, p-broom benzenesulfonyl, trifluoromethanesulfonyl or methanesulfonyl, most preferably methanesulfonyl. Agents commonly used for producing sulfonic acid esters e.g. are the halogenides or the anhydrides of the following sulfonic acids: methanesulfonic acid, p-toluenesulfonic acid a p-nitrobenzenesulfonic acid, p-bromobenzenesulfonic acid or trifluoromethanesulfonic acid. Preferred agent is a halogenide or anhydride of methanesulfonic acid such as methane sulfonylchloride. The sulfonylating agent is expediently added in an amount of 1.0 to 1.2 equivalents relating to one equivalent of the cyclohexene aziridine of formula (V). ' Usually the reaction takes place in an inert solvent such as in ethylacetate, at a reaction temperature of 0°C to 20°C and in the pretence of an organic base. For effecting the ring opening of the aziridine ring further the 0-substituted cyclopean derivative of formula (V) is converted with an alcohol R'OH, wherein R' is as above, in the presence of a Lewis acid. Following the preferences of R given above most suitable alcohol is pentane-3-ol. A suitable Lewis acid is e.g. bortrifluoride ethyl iterate which is usually added in an amount of 1.0 equivalent to 1.5 equivalents relating to one equivalent of the cyclohexene aziridine of formula (V). The reaction expediently takes place in an inert solvent such as in a halogenated hydrocarbon like methylene chloride at temperatures between 0°C and 40°C. Alternatively the reaction can be performed without extra solvent thereby using the respective alcohol in sufficient excess. Step f) Step f) covers the removal of R5 to yield the 4-amino cyclohexene derivative of formula (VII). R as outlined above preferably being daily phosphoryl is advantageously spitted off using strong acidic conditions. Suitably a strong mineral acid such as sulfuric acid can be used. In order to achieve better crystallization the sulfate formed can be transformed with hydrochloric acid into the hydro chloride. ,, The reaction conveniently takes place in a polar organic solvent such as in alcohols, preferably in alcohols which correspond to the ester residue R". Step g) As shown above step g) offers two different ways to come to the 4,5-diamino shikimic cid derivative of formula (I). One way comprising the steps gin to g23 passes an azide intermediate , whereby the other way comprising steps g21to g23 follows an azide free route. Preferred route is the azide free route g21 to g23. Steps gii to gi3 Step-in) The transformation of the 4-amino cyclohexene derivative of formula (VII) to the aziridine of formula (VIII) can happen by reaction with a tertiary amine in the presence of an inert solvent. Preferably triethylamine is selected as tertiary amine. The tertiary amine as a rule is applied in amounts of 2.0 equivalents to 2.5 equivalents relating to one equivalent of 4-amino cyclohexene derivative of formula (VII). The choice of solvents is not critical. Good results have been achieved with ethylacetate or tetrahydrofuran. The reaction usually takes place at a temperature of 40°C to 80°C. steps gi2, gl3 These steps comprise the conversion of the aziridine of formula (VIII) to an azide and the subsequent reduction to the end product. These steps are known in the art and can be processed following the disclosure in scheme 5 of J.C.Rohloff et al., J.Org.Chem., 1998, 63, 4545-4550 and the corresponding experimental part thereof, which is incorporated herein by reference. Steps g21 to g23 stepg2i) Step g21) comprises the transformation of the 4-amino cyclohexene derivative of formula (VII) into a 5-N-substituted-4,5-diamino shikimic acid derivative of formula (X). This transformation is expediently effected with an amine o f formula R'NHR', wherein R' and R8 have the meaning as stated above. Preferred amines are allylamine, diallylamine or 2-methylallylamine whereby allylamine is the most preferred. In order to release the amine the salt of the 4-amino cyclohexene derivative of formula (VII) as obtained in step f) is expediently neutralized first, either by addition of a common inorganic base such as sodium bicarbonate or by using the amine formula R^NHR* in excess. The reaction with the amine itself can be performed in an inert solvent, applying either normal or elevated pressure at temperatures of 20°C to 150°C. As a suitable solvent tert.-butyl methyl ether can be selected. Step g22) Step g::) comprises the acylation of the free amino function of the 5-N-substituted 4,5-diamino shikimic acid derivative of formula (X). Acylation can be effected under strong acidic conditions by using acylating agents known to the skilled in the art. Acylating agent can be an aliphatic or aromatic carboxylic acid, or an activated derivative thereof, such as an acyl halide, a carboxylic acid ester or a carboxylic acid anhydride. Suitable acylating agent preferably is an acetylating agent such as acetylchloride, trifluoracteylchloride or acetic anhydride. Suitable aromatic acylating agent is benzoylchloride. Strong acids suitably used e.g. are mixtures of methanesulfonic acid and acetic acid or sulfuric acid and acetic acid. Vacillations however can also take place under non acidic conditions using e.g. N-acetyl-imidazole or N-acetyl-N-methoxy-acetamide. Preferably however the acylation takes place under acidic conditions using 0.5 to 2.0 equivalents of acetic anhydride, 0 to 15.0 equivalents of acetic acid and 0 to 2.0 equivalents of methanesulfonic acid in ethyl acetate. An inert solvent such as tert.-butyl methyl ether may be added, it is however also possible to run the reaction without addition of any solvent. The temperature is as a rule chosen in the range of-20°C to 100°C. Step g23) Step g23) comprises release of the amino group in position 5 and, if necessary, further transformation of the resulting 4,5-diamino shikimic acid derivative of formula (I) into a pharmaceutically acceptable addition salt. Release of the amino group is expediently effected by isomerization/hydrolysis in the presence of a suitable metal catalyst. Expediently a precious metal catalyst such as Pt, Pd or Rh either applied on an inert support such as charcoal or alumina, or in complexes form can be used. Preferred catalyst is 5 to 10% palladium on carbon (Pd/C). The catalyst is suitably used in an amount of 2 to 30 wt.%, preferably, 5 to 20 vvt.% relating to the 5-N-substituted 4,5-diamino shikimic acid derivative of formula (X). The isomerization/hydrolysis is advantageously carried out in an aqueous solvent. The solvent itself can be protic or aprotic. Suitable protic solvents are e.g. alcohols such as methanol, ethanol or isopropanol. Suitable aprotic solvent is e.g. acetonitrile or dioxide. The reaction temperature is preferably chosen in the range of 20°C and 150°C. It was found that isomerization/hydrolysis is preferably effected in the presence of a primary amine. Primary amines suitably used are ethylenediamine or ethanolamine, or suitable derivatives thereof A particularly interesting primary amine is ethanolamine. The primary amine is suitably used in an amount of 1.0 to 1.25 equivalents, preferably of 1.05 to 1.15 equivalents relating to the 5-N-substituted 4,5-diamino shikimic acid derivative of formula (X). In order to completely hydrolyze any imines that may have formed in this step the reaction mixture is usually treated with a mineral acid e.g. with sulfuric acid or hydrochloric acid. Though the 4,5-diamino shikimic acid derivative can be isolated e.g. by evaporation and crystallization, it is preferably kept in e.g. an ethanolic solution and then further transformed into the pharmaceutically acceptable addition salt following the methods described in J.C.Rohloff et al., J.Org.Chem., 1998, 63; 4545-4550; WO 98/07685). The term "pharmaceutically acceptable acid addition salts" embraces salts with inorganic and organic acids, such as hydrochloric acid, hydrotropic acid, nitric acid, sulfuric acid, phosphoric acid, citric acid, formic acid, numeric acid, malefic acid, acetic acid, succinic acid, tartaric acid, methanesulfonic acid, p-toluenesulfonic acid and the like. The salt formation is effected in accordance with methods which are known per se and which are familiar to any person skilled in the art. Not only salts with inorganic acids, but also salts with organic acids come into consideration. Hydrochlorides, hydro bromides, sulfates, nitrates, citrates, acetates, maleates, succinct, methansulfonates, p-toluenesulfonates and the like are examples of such salts. Preferred pharmaceutically acceptable acid addition salt is the 1:1 salt with phosphoric acid which can be formed preferably in ethanolic solution at a temperature of 50°C to -20°C. The invention further comprises a process for the preparation of the 2R-exo isomer of the bicyclo compound of formula This process is characterized by the treatment of the exo/endo mixture of the bicyclo compound of formula (III) as obtained from step a) with a Phase of the EC class 3. 1. 1. 3 or a lipoprotein lipase of the EC class 3.1. 1. 34, the lipases thereby specifically hydrolyze the 2S-exo isomer and leaving the 2R-exo isomer untouched. This specific process embodiment is identical to step b). , ■ The respective description is incorporated herein by reference. Accordingly, as stated under step b), preferred lipases are of the genus Candida antarctica. The invention further comprises a process for the preparation of an ranitidine of formula wherein R3is as above and wherein R5 is the residue of an azide. This process is characterized by the conversion of a 2R-exo isomer of the bicycle compound of formula wherein R is as above, with an azide. This conversion is identical to step e) of the multiuse synthesis described herein above. The respective description of step c) is incorporated herein by reference. Preferred azide as stated above is diphenyloxy-phosphoryl azide (DPPA). wherein R is as above and wherein R is an azide residue, wherein R' and R are as above, preferably (lS,5S,6S)-7-(diethoxyphosphoryl)-5-hydroxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester (with R1 = ethyl and R2 = dithery-phosphoryl). wherein R1, R2 R3 are as above and its pharmaceutically acceptable salts, preferably (3R,4S,5S)-4-am:no-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-l-ene carboxylic acid ethyl ester hydrochloride (with R' = 1-ethylpropyl, R" = ethyl, R = methanesulfonyl . DUPLICATE Accordingly, the present invention provides a process for the preparation of a 4,5-diamino shikimic acid derivative of formula and phamiaceutical acceptable addition salts thereof wherein R1 is an optionally substituted alkyl group having 1 to 2 carbon atoms, R is an alkyl group him 1 to 20 carbon atoms and R3 and R4, independent of each other are H or a substituent of an amino group, with the proviso that not both R3 and R4 are H, comprising wherein R1 R2 and R3 are as defined herein above and converting said 4-amino cyclohexene derivative of formula (VII) to the 4,5-diamino shikimic acid derivatives of formula (I) and pharmaceutically acceptable salts thereof in a known manner and isolating the said compound I in a known manner. The following examples shall illustrate the invention in more detail without limiting it. Example 1: Preparation of 7-oxa-bicyclo[2.2.1]hept-5-ene-2-carhoxylic acid ethyl ester (endo/exomixture) A mixture of 300 g of furan (4.32 mol) and 611 g (6.05 mol) of ethyl acryl ate was cooled to 3°C in an ice bath under an inert atmosphere. 706 g (5.2 mol) of zinc chloride were added portionwise to the solution during 30 min, maintaining the temperature at between 10°C and 20°C. After completed addition, the cooling bath was removed and the mixture was allowed to gradually heat up during 30 min to 50°C by exothermic. It was subsequently kept at 50°C during 27 h by means of an oil bath, then cooled to 40°C and diluted with 200 ml of dichloromethane in order to reduce its viscosity. The solution was subsequently cooled to room temperature, poured on a mixture of 1.0 kg of crushed ice and 1.5 1 of water and extracted. The aqueous phase was extracted with 2.5 1 of ethyl acetate, and the combined organic phases were subsequently washed with 2.51 of water, a solution of 109 g sodium bicarbonate in 2.5 1 water, and 250 ml of brine. The organic phase was dried over sodium sulfate, filtered, evaporated at 45°C / 1 mbar and dried at 40°C / 0.06 mbar for 45 min, to yield 580 g (80%) of a 87:13 exo/endo mixture of product. Purity': 98% (HPLC; ISTD). Data of exo-isomer: IR (film): 2984, 1734, 1448, 1370, 1343, 1315, 1277, 1217, 1098, 1047, 1019, 907, 874, 808, 722, 704 cm -1; MS (EI, 70 eV): 139, 123, 94, 81, 68, 55, 41, 39, 29 m/z. Data of undo-isomer: IR (film): 2984, 1736, 1451, 1370, 1337,1320,1304, 1194, 1131, 1095, 1055, 1025, 905, 855, 795, 712, 702 cm -1; MS (EI, 70 eV): 139, 123, 99, 95, 81, 68, 55, 43, 41,39, 29 m/z. Example 2: Preparation of (lS,2R,4S)-7-oxa-bicyclo[2.2.1]hept-5-ene-exo-2-carboxylic acid ethyl ester 507.5 g (2.77 mol) of a 92:8 exo/endo-mixture of raceme 7-oxa-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid ethyl ester was emulsified in 5.7 1100 mM potassium chloride, 3 mM potassium phosphate buffer pH 7 and 3.71 of octane ('Octane Fraction', Fluka 74830) by vigorous stirring. The emulsion was cooled to 1°C and the pH adjusted to 7.5 with IN NaOH solution. After addition of 0.75 MU of Charisma L-2 (Roche Diagnostics) the pH was maintained at 7.5 under vigorous stirring at 1°C by the controlled addition (pH-stat) of 2.0 N NaOH-solution. After a total consumption of 930 ml 2.0 N NaOH-solution (corresponds to ca. 67% conversion with respect to the exam-isomer) after 10.6 h the reaction mixture was extracted with 3x81 dichloromethane (the first time the emulsion was passed through a bed of 500 g dicalite filter aid in order to enhance phase separation; the solvent for the second extraction step was passed through the filter bfed prior to use). The combined organic phases were dried on sodium sulfate, evaporated and dried on a high vacuum to give 160.5 g of a brownish oil. According to GC the title compound (93% eel) contained 20.5% of the endo-isomer, which was mostly removed from the mixture by distillation at 82°C-86°C / 3 mbar. Data of exo-isomer: IR (film): 2984, 1734, 1448, 1370, 1343, 1315, 1277, 1217, 1098, 1047, 1019, 907, 874, 808, 722, 704 cm -1; MS (EI, 70 eV): 139, 123, 94, 81, 68, 55, 41, 39, 29 m/z. Example 3: Preparation of (lS,2S,4R,5R,6R)-3-(diethoxyphosphoryl)-8-oxa-3-aza-tricyclo[3.2.1.0 2,4]octane-6-carboxylic acid ethyl ester A solution of 32.3 g (192 mmol) of (lS,2R,4S)-7-oxa-bicyclo[2.2.1]hept-5-ene-exo-2-carboxylic acid ethyl ester and 48.4 g (167 mmol) diphenylphosphoryl azide in 32 ml of toluene was stirred at 70°C for 18 h. Then 260 ml of ethanol were added, the mixture was cooled to 3°C and 150 ml (403 mmol) of 21% sodium ethyl ate solution were added during 15 min, allowing the mixture to reach room temperature. The mixture was stirred for 30 min at room temperature, then poured on a solution of 650 g of crushed ice in 650 ml of brine. The aqueous phase was extracted twice with 650 ml of ethyl acetate, the combined organic phases were dried over sodium sulfate, filtered and evaporated to give 64.8 g of crude product, which was subsequently chromatographer over silica gel with a 9:1 mixture of ethyl acetate and dioxin as the element, yielding 32.5 g (53%) of the product as an oil. Purity: 99% (ISTD). IR (film): 3741, 2983, 2908,1735,1479, 1445,1393,1369, 1356, 1299, 1265, 1184, 1097, 1042, 983, 925, 897, 864, 833, 800, 740, 673 cm '; MS (EI, 70 eV): 320 (MH+), 290, 274, 262, 246, 234, 219, 191, 163,109, 91, 81, 65, 55, 39 m/z. Example 4: Preparation of (lS,5S,6S)-7-(diethoxyphosphoryl)-5-hydroxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester A solution of 64.1 g (197 mmol) of (lS,2S,4R,5R,6R)-3-(diethoxyphosphoryl)-8-oxa-3-aza-tricyclo[3.2.1.0 2,4]octane- 6-carboxylic acid ethyl ester in 320 ml of THF was cooled to -65°C. Then 148 ml (296mmol) of 2 M sodium-bis-(trimethylsilyl)-amide in THF were added dropwise during 20 min, maintaining the temperature at below -60°C. The mixture was stirred at -60°C for 5 h, then 1.20 1 of ammonium chloride solution were added to the cold mixture, allowing it to reach 0°C after completed addition. 110 ml of water were added to the suspension to give a clear solution, which was stirred for 30 min while reaching room temperature. The solution was extracted with 1.60 1 of ethyl acetate, and the organic layer was washed with 60 ml of saturated sodium bicarbonate, dried over sodium sulfate, filtered and evaporated to give 57.1 g (91%) of product as an oil. Purity: 94% (ISTD). Optical rotation of further purified material: [a]D2o = -37.7°(c=l, EtOH). IR (film): 3381, 2983, 2910,1712, 1647, 1446, 1393,1258, 1213, 1165, 1136,1096, 1028, 960, 932, 882, 848, 821, 801, 771, 748, 707, 655 cm'; MS (EI, 70eV): 319 (M+), 301, 290, 273, 262, 246, 234, 216, 202, 188, 174, 165, 137, 119,109, 99, 91, 81, 65, 53, 45 m/e. Example 5: Preparation of (3R,4S,5S)-4-(diethoxyphosphorylainino)-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-1-enecarboxylic acid ethyl ester > A solution of 25.13 g (78.7 mmol) of (lS,5S,6S)-7-(diethoxyphosphoryl)-5-hydroxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester and 9.61 g (94.4 mmol) of triethylamine in 250 ml of ethyl acetate was cooled to 0°C. 10.0 g (94.4 mmol) of methanesulfonic acid chloride were added dropwise during 10 min, maintaining the temperature below 10°C. After completed addition, the mixture was allowed to reach room temperature during 20 min, and the triethylamine hydro-chloride precipitate was filtered off and washed in several portions with a total of 75 ml of ethyl acetate. The combined filtrates were evaporated to give 35.1 g of a brownish oil, which was sub-squinty dissolved in 75 ml of dichloromethane. 220 ml (2.03 mol) of 3-pentanol were added, the mixture was cooled to 0°C, and 14.8 ml (118 mmol) of BF3*OEt2 were added during 10 min, maintaining the temperature at below 4°C. After completed addition, the mixture was stirred for 1.5 h at room temperature. The crude reaction mixture was evaporated at 30°C (removal of excess of 3-pentanol), and the resulting oil was partitioned between 500 ml of ethyl acetate and 250 ml of saturated sodium bicarbonate solution. The organic layer was washed with 20 ml of brine, dried over sodium sulfate, filtered and evaporated to give 36.4 g of a brownish solid. Purification: 36.3 g of above crude product was taken up in 240 ml of ethyl acetate and heated to 60°C to give a clear solution. The solution was allowed to gradually cool to room temperature during 2 h, being seeded with product crystals at 50°C. The resulting suspension was stirred for 1 h at room temperature, filtered, washed portionwise with a total of 35 ml of ethyl acetate, and dried at 45°C / 5 mbar for 30 min to give a first portion of 15.67 g product as white crystals. The combined mother liquor and washings were evaporated, taken up in a mobster 50 ml of ethyl acetate and 25 ml of n-heptane and heated to 70°C. The mixture was allowed to cool to room temperature during 1.5 h, being seeded with product crystals at 50°C. The suspension was stirred for 15 min at room temperature and filtered. The residue was washed with a mixture of 7.5 ml of ethyl acetate and 2.5 ml of n-heptane and dried at 45°C / 5 mbar for 45 min to give a second portion of 8.28 g product as white crystals. Both product portions were combined to give 23.95 g (63%) product. m.p. 140.5 - 141.0°C. Purity: 95o/o (ISTD). Optical rotation of further purified material: [a]D2o = -26.5°(c=l,EtOH). IR (film): 3210, 2925, 2854, 1720, 1663, 1466, 1351,1286, 1252, 122],i 1175, 1156. 1142, i 1107, 1070, 1040, 966, 915, 895, 838, 811, 782. 748, 732 cm'; MS (Ell 70 eV): 486 (M+), 416, 398, 320, 302. 286, 274. 246 m/e. Example 6: Preparation of (3R.4S.5S)-4-amino-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-1-enecarboxylic acid ethyl ester hydrochloride A solution of 22.07 g (41.4 mmol) of (3R.4S.5S)-4-(diethoxyphosphorylamino)-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-l-enecarboxylic acid ethyl ester in 90 ml of ethanol was cooled to 0°C. 22 ml (395 mmol) of 96% sulfuric acid were added dropwise during 25 min. maintaining the temperature at below 20°C. After completed addition, the mixture was stirred for 22 h at 70°C, then cooled to 0° and poured on an ice cold mixture of 1.0 1 of ethyl acetate and 1.01 of 10% (w/v) sodium hydroxide solution. After extraction, the phases were separated and the organic phase was washed with 280 ml of water, dried over sodium sulfate, filtered and evaporated to give 14,9 g of crude product. This material was taken up in 90 ml of tert.-butyl methyl ester, the suspension heated to 50°C to give a clear, brownish solution, and cooled to 10°C, where 30 ml of 4M HCl in ethanol were added, maintaining the temperature at below 20°C. After about 1 minute the product started to precipitate. The thick suspension was diluted with 50 ml of n-hexane and stirred for 15 min at room temperature. The precipitate was filtered off and dried at 40°C / 3 mbar for 30 min to give 11.09 g ( 63%) of product as white crystals. IR (film): 3233, 2923, 2853. 2687, 2579, 1989, 1717, 1654, 1586, 1487, 1464, 1357,1340, 1266, 1225, 1177, 1067, 1021, 973, 940, 906, 885, 830, 747, 729 cm"'. Example 7: Preparation of (3R,4R,5S)-5-allylamino-4-amino-3-(l-ethyl-propoxyl-cydohex-l-enecarboxylic acid ethyl ester A solution of 6.95 g (19.9 mmol) of (3R,4S,5S)-4-amino-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-l-enecarboxylic acid ethyl ester hydrochloride and 6.1 ml (79. 6 mmol) of allylamine in 82 ml of tert.-butyl methyl ester was sealed in a pressure vessel under argon and heated to 110°C, resulting in a 4 bar internal pressure. After 20 h the mixture was cooled to room temperature and partitioned between 30 ml of tert.-but\'l methyl ester and 120 ml of saturated sodium bicarbonate solution. The aqueous phase was extracted with 50 ml tert.-butyl methyl ester, and the combined organic phases were dried over sodium sulfate, filtered and evaporated to give 5.90 g (96%) of product as a slightly brownish oil. Purity: 77% (ISTD). IR(film): 3274, 3084, 2925, 2853, 1721, 1645, 1556, 1457, 1373, 1318, 1249, 1185, 1130, 1087, 1057, 1037, 995, 938, 770, 736; MS (70 eV): 353 (M+), 296, 283, 265, 226 m/e. Example 8: Preparation of (3R,4R,5S)-4-acetylamino-5-allylamino-3-(l-ethyl-propoxy)-cyclohex-1-enecarboxylic acid ethyl ester In a 414-necked round bottom flask equipped with a thermometer, a mechanical stirrer, a Claisen condenser and an inert gas supply 278.0 g of (3R,4R,5S)-5-aIlylamino-4-amino-3-(l-ethyl-propoxy)-cyclohex-l-enecarboxylic acid ethyl ester obtained according to (c ) were dissolved at room temperature with stirring under argon in 2800 ml of tert.-butyl methyl ether. From the red solution 1400 ml of tert.-butyl methyl ether were distilled. Again 1400 ml of tert.-butyl methyl ether were added and distilled off. The red solution was cooled to 0-5°C and treated with 512 ml of acetic acid (9.0 mol) whereby the temperature rose to about 23°C. After cooling to 0°C-5°C 58.1 ml of methanesulfonic acid (d= 1.482, 0.90 mol) were added dropwise in the course of 27 min followed by 84.7 ml of acetic anhydride (d=1.08, 0.90 mol) added dropwise in the course of 40 min keeping the temperature in the range of 0°C to 5°C. The brown reaction mixture was stirred without cooling for 14 h then treated with vigorous stirring with 1400 ml of water (deionized) for 30 min and the brown organic phase was extracted with 450 ml of IM aqueous methanesulfonic acid. The combined aqueous phases (pH=1.6) were treated with stirring with about 694 ml of 50% aqueous potassium hydroxide until pH=10.0 was reached, keeping the temperature in the range of 10 to 25°C. The brown, turbid mixture was extracted first with 1000 ml then with 400 ml, in total with 1400 ml of tert.-butyl methyl ether, the combined organic extracts were stirred over 32 g of charcoal and filtered. The filter cake was washed with about 200 ml tert.-butyl methyl ether and the combined filtrates were evaporated in a rotary evaporator at 47°C / 380 to 10 mbar to yield 285.4 g of brown-red, amorphous crystals which were dissolved with stirring in a mixture of 570 ml of tert.-butyl methyl ether and 285 ml of n-hexane at 50°C. The brown solution was cooled in 45 min with stirring to -20°C to -25°C and stirred for 5 h whereby brown crystals precipitated. The suspension was filtered over a pre-cooled (-20°C) glass filter funnel and the filter cake was washed with a pre-cooled (-20°C) mixture of 285 ml of tert.-but>'l methyl ether and 143 ml of n-hexane and dried in a rotary evaporator at 48°C Example 9: Preparation of (3R,4R,5S)-4-acetylamino-5-amino-3-(l-ethyl-propoxy)-cyclohex-1 -enecarboxylic acid ethyl ester In a 11 4-necked round bottom flask equipped with a thermometer, a mechanical stirrer, a reflux condenser and an inert gas supply 176.2 g of (3R,4R,5S)-4-acetylamino-5- aIIylamino-3-(l-ethyl-propoxy)-cyclohex-l-enecarboxylic acid ethyl ester obtained according to example 8 and 30.0 ml of ethanolamine (d=1.015, 0.54 mol) were dissolved at room temperature in 880 ml of ethanol and treated with 17.6 g of 10% palladium on charcoal. The black suspension was heated to reflux for 3 h, cooled to room temperature and filtered. The filter cake was washed with 100 ml of ethanol and the combined filtrates t f were evaporated in a rotary evaporator at 50°C / (3R,4R,5S)-4-acetylamino-5-amino-3-(l-ethyl-propoxy)-cyclohex-l-enecarboxylicacid ethyl ester as white crystals; m.p. 205-207°C, decomposition. WE CLAIM; 1. A process for the preparation of a 4,5-diamino Chichimec acid derivative of formula and phamiaceutical acceptable addition salts thereof wherein R1 is an optionally substituted alkyl group having 1 to 2 carbon atoms, R2 is an alkyl group having 1 to 20 carbon atoms and R3 and R4, independent of each other are H or a subsistent of an amino group, with the proviso that not both R3 and R4 are H, comprising step a) • furan is reacted in a known manner with an acrylic acid wherein R2 is as above and R5 is an aide residue then, in wherein R2 and R5 are as defined herein above, step e) a subsistent R6 is introduced in a known manner in the free OH- monition wherein R1,R2 and R6 are as defined herein above and converting said 4-ainino cyclohexene derivative of formula (VII) to the 4,5-diamino Chichimec acid derivatives of formula (I) and phamiaceutical acceptable salts thereof in a known manner and isolating the said compound I in a known manner. 2. The process as claimed in claim 1 wherein said compound of formula VII is converted into compounds of formula I by transformation into an ranitidine of formula wherein R' and R^ are defined herein above, by reacting with a tertiary amine and converting said ranitidine of formula VIII to the azide of formula wherein R1 R2, R3 and R4 are as defined herein above in a known manner followed by reducing the said compound of formula DC in a known manner and converting the same to the pharmaceutically acceptable addition salt in a known manner. V . %r hi■■--' The process as claimed in claim 1 wherein the transformation of 4-amino cyclohexene derivative of the formula VII into a 5-N-substituted-4,5-diamino shikimic acid derivative of formula wherein R^ and R' are as herein defined above and R1and R2, independent of each other are H or a substituent of an amino group, with the proviso that not bola R7 and R8 are H by reacting with an amine of tbnnula R7NHR8 acieration of the amino group in position 4 in a known manner and releasing the amino group in position 5 in a known manner and, if necessary, the formation of the phamiaceutical acceptable addition salt by known metalloids. 4. The process as claimed in claim I, wherein step (a) is performed in tlie presence. of a Lewis acid. 5. The process as claimed in claim 4, wherein the Lewis acid is zinc chloride used in stoechiometric amounts relating to the bicyclo compound of formula (III). 6. The process as claimed in claims 1 to 3, wherein separation of the 2R-e.xo isomer of the bicyclo compound of formula (III) is effected by means of a lipase of the EC class 3.1.1.3 or a lipoprotein lipase of the EC class 3.1.1.34, both lipase being capable to specifically hydrolyze the 2S-exo isomer of the bicyclo compound of formula (III) only, and by separation of the 2R-exo isomer from the end isomers by subsequent distillation. ■/ ^^TT^ ■ 5 FEB ZQ03 7. The process as claimed in claim 6, wherein said lipase is of the genus Candida antarctica. 8. The process as claimed in claims 1 to 7, wherein the a2ide used in step (c) to form the aerodyne of formula (IV) is diphenyl phosphoric azide. 9. The process as claimed in claims 1 to 8, wherein the elimination ring opening in step (d) is effected in the presence of a strong organic base such as herein described. 10. The process as claimed in claim 9, wherein said strong organic base is an alkali-bis-(trimethylsilyi) amide. 11. The process as claimed in claim 1, wherein step (e) comprises the transformation of the OH-group into a sulfuric acid ester. 12. The process as claimed in claim 11, wherein a methanesulfonic acid ester is formed. 13. The process as claimed in claims 1 to 12, wherein the removal of R5 in step (f) is carried out under strong acidic conditions. - - ^ 14. A process for the preparation of a 4,5-diamino shikimic acid derivative substantially as herein described and exemplified.

Full Text

The present invention relates to a multi step process for the preparation of 4,5-diamino Chichimec acid derivatives, especially for the preparation of (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxylic acid ethyl ester and its pharmaceutically acceptable addition salts starting from furan as well as new specific intermediates.
4,5-diamino shikimic acid derivatives, especially the (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxylic acid ethyl ester and its pharmaceutically acceptable addition salts are potent inhibitors of viral neuraminidase ( J.C.Rohloff et al., J.Org.Chem., 1998, 63, 4545-4550; WO 98/07685).
A multi step synthesis of (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-1-carboxylic acid ethyl ester from (-)-quince acid or (-)-Chichimec acid is described in (J.C.Rohloff et al, loc.cit.).
Both (-)-quinic acid and (-)-shikimic acid are starting compounds which are rather expensive and hardly accessible in technical quantities. A multi step synthesis capable to run on a technical scale should therefore preferably be based on starting compounds which are more attractive in price and available in technical quantities.
Object of the present invention therefore is to provide such a new access to the 4,5-diamino shikimic acid derivatives mentioned above in good yields and excellent quality.
It was found that with the synthesis according to claim 1 this object could surprisingly be achieved.
The present invention therefore relates to a process for the preparation of a 4,5-diamino shikimic acid derivative of formula
RAU/20.12.2000

and pharmaceutically acceptable addition salts thereof
wherein
R1 is an optionally substituted alkyl group,
R is an alkyl group and
R and R , independent of each other are H or a substation of an amino group, with the proviso that not both R3 and R4 are H, a process
which is characterized in that in

step b)
the 2R-exo isomer of the bicycle compound of formula (III) is separated, in

step c)
this 2R-exo isomer of the biked compound of formula (III) is reacted with an azide to form an ranitidine of formula

wherein R" is as above and wherein R^ is the residue of an azide the
step d)
wherein R^ and R^ are as above , in
step e)
a constituent R* is introduced in the free OH-position and the ranitidine ring is opened to give a cyclohexene derivative of formula

wherein R1, R2 and R5 are as above and R6 is a subsistent of an OH group, in

step f)
R5 is removed to yield a 4-amino cyclohexene derivative of formula

wherein R1, R2 and R6 are as above
this 4-amino cyclohexene derivative of formula (VII) is finally processed to the 4,5-diamino shikimic acid derivatives of formula (I) by
step g)
comprising either gn transformation of the 4-amino cyclohexene derivative of formula (VII) into an ranitidine of formula
wherein R' and R' are as above,
gi2 formation of the azide of formula

gi3 reduction and, if necessary the formation of the pharmaceutically acceptable addition salt,

wherein R1 and R" are as above and R' and R^, independent of each other are H or a substituent of an amino group, with the proviso that not both
R7 and R8 are H
g22 vacillation of the amino group in position 4 and
g23 releasing the amino group in position 5 and, if necessary the formation of the pharmaceutically acceptable addition salt.

The term alkyl in R'1 has the meaning of a straight chained or branched alkyl group of 1 to 20 C-atoms, expediently of 1 to 12 C-atoms. Examples of such alkyl groups are methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, tert.-butyl, pentyl and its isomers, hexyl and its isomers, hotly and its isomers, octyl and its isomers, nonyl and its isomers, dactyl and its isomers, unequal and its isomers and dodecyl and its isomers.
>
This alkyl group can be substituted with one or more substituents as defined in e.g. WO 98/07685. Suitable substituents are alkyl of 1 to 20 C-atoms (as defined above), alkenyl with 2 to 20 C-atoms, cycloalkyl with 3 to 6 C-atoms, hydroxy, alloys with 1 to 20 C-atoms, alkoxycarbonyl with 1 to 20 C-atoms, F, CI, Br, and J. Preferred meaning forR'isl-ethylpropyl.
R" is a straight chained or branched alkyl group of 1 to 12 C-atoms, expediently of 1 to 6 C-atoms, as exemplified above.
Preferred meaning for R2 is ethyl.
The substituent R6 refers to any substitute for OH groups conventionally used and kno\s'n in the art. They are described e.g. in "Compendium of Organic Methods" or in "Advanced Organic Chemistry", ed. March J., John Wiley & Sons, New York, 1992, 353-357.
Preferably R6 is a sulfonyl group, more preferably optionally substituted aryl sulfonyl or alkyl sulfonyl such as p-toluenesulfonyl, p-nitrobenzenesulfonyl, p-bromo benzenesulfonyl, trifluoromethanesulfonyl or methanesulfonyl, most preferably methanesulfonyl.
The term substituent of an amino group in R" and R** or R' and R^ refers to any substituent conventionally used and known in the art. They are described e.g. in "Protective Groups in Organic Chemistry", Theodora W. Greene et al., John Wiley 8 Preferred substituents for R3 and R4 are alkanoyl groups, more preferably lower alkanoyl with 1 to 6 C-atoms such as humanely, pentanoyl, butanoyl (butyryl), propanoyl (propionyl), ethanoyl (acetyl) and methanoyl (formal). Preferred alkanoyl group and therefore preferred meaning for R' is acetyl and for R^ is H.

Preferred substituent for R7 and R8 is straight chained or branched alkenyl with 2 to 6 C-atoms, preferably ally or an analog thereof. Suitable analog of alkyl is an alkyl group which is substituted on the a-, j8-or y-carbon by one lower alkyl, lower alkenyl, lower alkynes or aryl group. Suitable examples are e.g. 2-methylallyl, 3,3-dimethylallyl, 2-phenylallyl, or 3-
methallyl. Most preferred meaning for R^ is alkyl and for R* is H.
.'
Preferred 4,5-diamino shikimic acid derivative of formula (I) is the (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxylic acid ethyl ester and the ethyl (3R,4R,5S)-4-acetamido-5-amino-3-(l-ethylpropoxy)-l-cyclohexene-l-carboxyl ate Phosphate (1:1)
Step a)
Step a) comprises a Diels-Alder reaction of furan with an acrylic acid derivative. Diels-Alder reactions per se are known to the skilled in the art (see e.g. Tetrahedron Letters, 23, 1982, 5299-5302). The present conversion can therefore be performed following the methods and conditions described in the art.
Suitable derivatives of an acrylic acid are the esters and the amides, preferably the esters, more preferably lower alkyl esters of acrylic acid.
Usually this type of reaction needs the presence of Lewis acids. Suitable Lewis acids are magnesium halogenides such as magnesium chloride, magnesium bromide or magnesium iodide or zinc halogenides such as zinc chloride, zinc bromide or zinc iodide. Preferred Lewis acid was found to be zinc chloride.
As a rule catalytic amounts of the Lewis acid are applied, however it was surprisingly found that stoechiometric amounts or even an excess of the Lewis acid, preferably of zinc chloride within a reasonable time lead to an excellent exo/endo ratio of the bicycle compound of formula (III) of up to 9:1.
Preferably stoechiometric amounts of zinc chloride are used.

!]convenient solvent for step a) is the reactant acrylic acid derivative itself, used m an excess of up to 50%. It is however always possible to add an inert solvent.
The reaction temperature can be chosen in the range of 20°C to 70°C.
\fter termination of the reaction work up can take place using methods well known to the skilled in the art.
Step b)
Step b) comprises separation of the 2R-exo isomer of the bicycio compound of formula (III), preferably of the optical pure 2R-exo isomer of the bicycio compound of formula (III).
Step a) provides the racemate of an exo/endo mixture of the bicycio compound, wherein the exo form in the mixture is enriched up to a ratio of 9:1.
As a principle separation of endo and exo forms of a compound can take place by taking advantage of the different physical properties of these forms such as different boiling points. Separation of each of the two optical isomers however have to take place either by classical racemate resolution techniques or by a stereo selective methods, e.g. by an enzymatic approach.
The desired 2R-exo form of the bicycio compound can accordingly be gained by physical separation of the exo and endo form e.g. by distillation, by converting the exo-ester into the respective acid and finally by a subsequent racemate resolution using classical resolving agents such as (-)-ephedrine hydrochloride or S-(-)-l-phenyl ethylamine.

Preferably, however the exo/endo mixture of step a) is treated with an enzyme which is capable to hydrolyze specifically the 2S-exo isomer only and which is leaving the 2R-exo isomer untouched. It was found that ideally lipases of the EC class 3.1.1.3 or lipoprotein lipases of the EC class 3.1.1.34 are used. Suitable representatives of tl?ese classes are lipases of the genus Candida, more preferably of Candida antarctica. Such lipases are commercially available. Most preferred enzyme is the B-form of lipase Candida antarctica
vv^hich is offered under the tradename Chirazyme©L2 from Roche Diagnostics or as Lipase SP-525 from Novo Nordisk.
As a common alternative immobilized enzymes maybe used.
The reaction is usually carried out in a monophasic or biphasic aqueous system, preferably in a biphasic system with an polar solvent as co-solvent. Suitable co-solvents are alkenes, cycloalkanes or cycloalkenes. Cyclohexane, cyclohexene and octane was found to be the most preferred co-solvent.
The common aqueous buffer solutions known to be used for biochemical conversions are used in order to maintain the pH in the range of 6.5 to 8.0. Suitably sodium or potassium phosphate buffers or borate buffers can be applied. Such a buffer solution can additionally contain NaCl or KCl in a concentration of 50 to 300 mM. A preferred buffering system could e.g. contain 0.1 M KCl and 5 mM potassium borate pH 7.5.
The ratio organic solvent / aqueous phase is in the range of 1:10 to 3:2. Overall substrate concentration is expediently chosen in the range of 5 to 20 wt.%, preferably in the range of 5 to 10 wt.%.
Suitable reaction temperature is 0°C to 25°C, preferably close to freezing temperature of the reaction mixture.

The resulting 2S-exo acid is preferably neutralized by the controlled addition of a base such as NaOH or KOH, whereby the unleaded 2R-exo ester together with the endo isomers remains in the organic phase and is separated by way of extraction with a common organic solvent.
Separation of the 2R-exo ester from the endo isomers can take place by a distillation in vacuous, preferably at a temperature in the range of 70°C and 100°C and a pressure of 0.1 mbar to 10 mbar.
Step c)
Step c) comprises the reaction of the 2R-exo isomer of the bicyclo compound of formula (III) with an azide.
Suitable azides are found to be these which are capable to form an aziridine ring in endo-position to the bridgehead of the bicyclic system. Unexpectedly phosphoryl azides of the formula
wherein R is dialkoxyphosphoryl or diaryloxyphosphoryl, preferably diaryloxyphosphoryl, most preferably diphenyloxyphosphoryl fulfilled this task.
Most preferred phosphoryl azide is the diphenyloxy-phosphoryl azide (DPPA).
The preference of DPPA is mainly based on its availability in technical quantities and its lower toxicity compared to the dialkoxyphosphoryl azides.
The phosphoryl azide is conveniently added in an amount of 0.8 equivalents to 1.0 equivalents relating to the 2R-exo bicyclo compound gained in step b). Preferably stoechiometric amounts of the phosphoryl azide are added.
The choice of a solvent is not critical as long as it is inert to the reactants. Toluene or dioxins were found to be suitable solvents.

The reaction temperature is chosen expediently between 40°C and 80°C.
In case R has the preferred meaning of diaryloxy phosphoryl, a trarliesterification can be performed to transform the diaryloxy phosphoryl group into a dialkoxy phosphoryl group.
Accordingly the azide residue R5 is dialkoxy-phosphoryl, preferably di-(Ci.6) alkoxy-phosphoryl, most preferably dithery-phosphoryl. Transesterifications are methods known to the skilled in the art, but as a rule take place in the presence of an alcoholate in the corresponding alcohol. Within the most preferred method transesterification takes place in the presence of sodium ethanol ate in ethanol.
Step d)
Step d) comprises eliminative ring opening of the aziridine of formula (IV) to the cyclohexene aziridine derivative of formula (V).
This reaction is performed in the presence of a strong organic base. Expediently alkali-bis -(trialkylsilyl) amides, preferably alkali-bis-(trimethylsilyl) amides such as lithium bis-(trimethylsilyl) amide, sodium-bis-(trimethylsilyl) amide or potassium-bis-(trimethylsilyl) amide are used.
Usually the strong organic base is used in amount of 1.0 equivalent to 2.5 equivalents relating to one equivalent of the aziridine of formula (V).
The choice of a solvent also for this step is not critical as long as it is inert to the reactants. Dioxins or tetrahydrofuran were found to be suitable solvents.

The reaction temperature is expediently maintained in the range of-80°C to 0°C, preferably in the range of-80°C to -20°C.
The cyclohexene aziridine of formula (V) can be isolated after an acidic work up applying methods known to the skilled in the art.
Step e)
Step e) comprises introduction of a substituent R^ in the free OH-position and ring opening of the aziridine ring to give cyclohexene derivatives of formula (VI).
The sequence, however can also be changed such that ring opening is first and introduction of substituent R^ in the free OH-position comes second. Preferably however is to first introduce substituent R into the free OH-position and to perform ring opening as second step.
Compounds and methods for effecting such a substitution are well known in the art and described e.g. in "Compendium of Organic Methods" or in "Advanced Organic Chemistry", ed. March J., John Wiley & Sons, New York, 1992, 353-357.
It was found that the hydroxy group is preferably transformed into a sulfonic acid ester, R therefore preferably is a sulfonyl group, more preferably optionally substituted aryl sulfonyl or alkyl sulfonyl such as p-toluenesulfonyl, p-nitrobenzenesulfonyl, p-broom benzenesulfonyl, trifluoromethanesulfonyl or methanesulfonyl, most preferably methanesulfonyl.
Agents commonly used for producing sulfonic acid esters e.g. are the halogenides or the anhydrides of the following sulfonic acids: methanesulfonic acid, p-toluenesulfonic acid a p-nitrobenzenesulfonic acid, p-bromobenzenesulfonic acid or trifluoromethanesulfonic acid.

Preferred agent is a halogenide or anhydride of methanesulfonic acid such as methane sulfonylchloride.
The sulfonylating agent is expediently added in an amount of 1.0 to 1.2 equivalents relating
to one equivalent of the cyclohexene aziridine of formula (V). '
Usually the reaction takes place in an inert solvent such as in ethylacetate, at a reaction temperature of 0°C to 20°C and in the pretence of an organic base.
For effecting the ring opening of the aziridine ring further the 0-substituted cyclopean derivative of formula (V) is converted with an alcohol R'OH, wherein R' is as above, in the presence of a Lewis acid. Following the preferences of R given above most suitable alcohol is pentane-3-ol.
A suitable Lewis acid is e.g. bortrifluoride ethyl iterate which is usually added in an amount of 1.0 equivalent to 1.5 equivalents relating to one equivalent of the cyclohexene aziridine of formula (V).
The reaction expediently takes place in an inert solvent such as in a halogenated hydrocarbon like methylene chloride at temperatures between 0°C and 40°C.
Alternatively the reaction can be performed without extra solvent thereby using the respective alcohol in sufficient excess.
Step f)
Step f) covers the removal of R5 to yield the 4-amino cyclohexene derivative of formula (VII).

R as outlined above preferably being daily phosphoryl is advantageously spitted off
using strong acidic conditions. Suitably a strong mineral acid such as sulfuric acid can be
used. In order to achieve better crystallization the sulfate formed can be transformed with
hydrochloric acid into the hydro chloride. ,,
The reaction conveniently takes place in a polar organic solvent such as in alcohols, preferably in alcohols which correspond to the ester residue R".
Step g)
As shown above step g) offers two different ways to come to the 4,5-diamino shikimic cid derivative of formula (I).
One way comprising the steps gin to g23 passes an azide intermediate , whereby the other way comprising steps g21to g23 follows an azide free route. Preferred route is the azide free route g21 to g23.
Steps gii to gi3
Step-in)
The transformation of the 4-amino cyclohexene derivative of formula (VII) to the aziridine of formula (VIII) can happen by reaction with a tertiary amine in the presence of an inert solvent.
Preferably triethylamine is selected as tertiary amine.

The tertiary amine as a rule is applied in amounts of 2.0 equivalents to 2.5 equivalents relating to one equivalent of 4-amino cyclohexene derivative of formula (VII).
The choice of solvents is not critical. Good results have been achieved with ethylacetate or tetrahydrofuran.
The reaction usually takes place at a temperature of 40°C to 80°C.
steps gi2, gl3
These steps comprise the conversion of the aziridine of formula (VIII) to an azide and the subsequent reduction to the end product. These steps are known in the art and can be processed following the disclosure in scheme 5 of J.C.Rohloff et al., J.Org.Chem., 1998, 63, 4545-4550 and the corresponding experimental part thereof, which is incorporated herein by reference.
Steps g21 to g23
stepg2i)
Step g21) comprises the transformation of the 4-amino cyclohexene derivative of formula (VII) into a 5-N-substituted-4,5-diamino shikimic acid derivative of formula (X).
This transformation is expediently effected with an amine o f formula R'NHR', wherein R' and R8 have the meaning as stated above. Preferred amines are allylamine, diallylamine or 2-methylallylamine whereby allylamine is the most preferred.

In order to release the amine the salt of the 4-amino cyclohexene derivative of formula (VII) as obtained in step f) is expediently neutralized first, either by addition of a common inorganic base such as sodium bicarbonate or by using the amine formula R^NHR* in excess.
The reaction with the amine itself can be performed in an inert solvent, applying either normal or elevated pressure at temperatures of 20°C to 150°C. As a suitable solvent tert.-butyl methyl ether can be selected.
Step g22)
Step g::) comprises the acylation of the free amino function of the 5-N-substituted 4,5-diamino shikimic acid derivative of formula (X).
Acylation can be effected under strong acidic conditions by using acylating agents known to the skilled in the art. Acylating agent can be an aliphatic or aromatic carboxylic acid, or an activated derivative thereof, such as an acyl halide, a carboxylic acid ester or a carboxylic acid anhydride. Suitable acylating agent preferably is an acetylating agent such as acetylchloride, trifluoracteylchloride or acetic anhydride. Suitable aromatic acylating agent is benzoylchloride. Strong acids suitably used e.g. are mixtures of methanesulfonic acid and acetic acid or sulfuric acid and acetic acid.
Vacillations however can also take place under non acidic conditions using e.g. N-acetyl-imidazole or N-acetyl-N-methoxy-acetamide.
Preferably however the acylation takes place under acidic conditions using 0.5 to 2.0 equivalents of acetic anhydride, 0 to 15.0 equivalents of acetic acid and 0 to 2.0 equivalents of methanesulfonic acid in ethyl acetate.

An inert solvent such as tert.-butyl methyl ether may be added, it is however also possible to run the reaction without addition of any solvent.
The temperature is as a rule chosen in the range of-20°C to 100°C.
Step g23)
Step g23) comprises release of the amino group in position 5 and, if necessary, further transformation of the resulting 4,5-diamino shikimic acid derivative of formula (I) into a pharmaceutically acceptable addition salt.
Release of the amino group is expediently effected by isomerization/hydrolysis in the presence of a suitable metal catalyst. Expediently a precious metal catalyst such as Pt, Pd or Rh either applied on an inert support such as charcoal or alumina, or in complexes form can be used. Preferred catalyst is 5 to 10% palladium on carbon (Pd/C).
The catalyst is suitably used in an amount of 2 to 30 wt.%, preferably, 5 to 20 vvt.% relating to the 5-N-substituted 4,5-diamino shikimic acid derivative of formula (X).
The isomerization/hydrolysis is advantageously carried out in an aqueous solvent. The solvent itself can be protic or aprotic. Suitable protic solvents are e.g. alcohols such as methanol, ethanol or isopropanol. Suitable aprotic solvent is e.g. acetonitrile or dioxide.
The reaction temperature is preferably chosen in the range of 20°C and 150°C.
It was found that isomerization/hydrolysis is preferably effected in the presence of a primary amine.
Primary amines suitably used are ethylenediamine or ethanolamine, or suitable derivatives thereof A particularly interesting primary amine is ethanolamine.
The primary amine is suitably used in an amount of 1.0 to 1.25 equivalents, preferably of 1.05 to 1.15 equivalents relating to the 5-N-substituted 4,5-diamino shikimic acid derivative of formula (X).

In order to completely hydrolyze any imines that may have formed in this step the reaction mixture is usually treated with a mineral acid e.g. with sulfuric acid or hydrochloric acid.
Though the 4,5-diamino shikimic acid derivative can be isolated e.g. by evaporation and crystallization, it is preferably kept in e.g. an ethanolic solution and then further transformed into the pharmaceutically acceptable addition salt following the methods described in J.C.Rohloff et al., J.Org.Chem., 1998, 63; 4545-4550; WO 98/07685).
The term "pharmaceutically acceptable acid addition salts" embraces salts with inorganic and organic acids, such as hydrochloric acid, hydrotropic acid, nitric acid, sulfuric acid, phosphoric acid, citric acid, formic acid, numeric acid, malefic acid, acetic acid, succinic acid, tartaric acid, methanesulfonic acid, p-toluenesulfonic acid and the like.
The salt formation is effected in accordance with methods which are known per se and which are familiar to any person skilled in the art. Not only salts with inorganic acids, but also salts with organic acids come into consideration. Hydrochlorides, hydro bromides, sulfates, nitrates, citrates, acetates, maleates, succinct, methansulfonates, p-toluenesulfonates and the like are examples of such salts.
Preferred pharmaceutically acceptable acid addition salt is the 1:1 salt with phosphoric acid which can be formed preferably in ethanolic solution at a temperature of 50°C to -20°C.
The invention further comprises a process for the preparation of the 2R-exo isomer of the bicyclo compound of formula

This process is characterized by the treatment of the exo/endo mixture of the bicyclo compound of formula (III) as obtained from step a) with a Phase of the EC class 3. 1. 1. 3 or a lipoprotein lipase of the EC class 3.1. 1. 34, the lipases thereby specifically hydrolyze the 2S-exo isomer and leaving the 2R-exo isomer untouched.
This specific process embodiment is identical to step b). , ■
The respective description is incorporated herein by reference.
Accordingly, as stated under step b), preferred lipases are of the genus Candida antarctica.
The invention further comprises a process for the preparation of an ranitidine of formula

wherein R3is as above and wherein R5 is the residue of an azide.
This process is characterized by the conversion of a 2R-exo isomer of the bicycle compound of formula

wherein R is as above, with an azide.
This conversion is identical to step e) of the multiuse synthesis described herein above. The respective description of step c) is incorporated herein by reference.

Preferred azide as stated above is diphenyloxy-phosphoryl azide (DPPA).

wherein R is as above and wherein R is an azide residue,

wherein R' and R are as above,
preferably (lS,5S,6S)-7-(diethoxyphosphoryl)-5-hydroxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester (with R1 = ethyl and R2 = dithery-phosphoryl).

wherein R1, R2 R3 are as above and its pharmaceutically acceptable salts, preferably
(3R,4S,5S)-4-am:no-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-l-ene carboxylic acid ethyl ester hydrochloride (with R' = 1-ethylpropyl, R" = ethyl, R = methanesulfonyl .
DUPLICATE

Accordingly, the present invention provides a process for the preparation of a 4,5-diamino shikimic acid derivative of formula

and phamiaceutical acceptable addition salts thereof wherein
R1 is an optionally substituted alkyl group having 1 to 2 carbon atoms,
R is an alkyl group him 1 to 20 carbon atoms and
R3 and R4, independent of each other are H or a substituent of an amino group,
with the proviso that not both R3 and R4 are H, comprising

wherein R1 R2 and R3 are as defined herein above and converting said 4-amino cyclohexene derivative of formula (VII) to the 4,5-diamino shikimic acid derivatives of formula (I) and pharmaceutically acceptable salts thereof in a known manner and isolating the said compound I in a known manner.
The following examples shall illustrate the invention in more detail without limiting it.
Example 1:
Preparation of 7-oxa-bicyclo[2.2.1]hept-5-ene-2-carhoxylic acid ethyl ester (endo/exomixture)

A mixture of 300 g of furan (4.32 mol) and 611 g (6.05 mol) of ethyl acryl ate was cooled to 3°C in an ice bath under an inert atmosphere. 706 g (5.2 mol) of zinc chloride were added portionwise to the solution during 30 min, maintaining the temperature at between 10°C and 20°C. After completed addition, the cooling bath was removed and the mixture was allowed to gradually heat up during 30 min to 50°C by exothermic. It was subsequently kept at 50°C during 27 h by means of an oil bath, then cooled to 40°C and diluted with 200 ml of dichloromethane in order to reduce its viscosity. The solution was subsequently cooled to room temperature, poured on a mixture of 1.0 kg of crushed ice and 1.5 1 of water and extracted. The aqueous phase was extracted with 2.5 1 of ethyl acetate, and the combined organic phases were subsequently washed with 2.51 of water, a solution of 109 g sodium bicarbonate in 2.5 1 water, and 250 ml of brine. The organic phase was dried over sodium sulfate, filtered, evaporated at 45°C / 1 mbar and dried at 40°C / 0.06 mbar for 45 min, to yield 580 g (80%) of a 87:13 exo/endo mixture of product. Purity': 98% (HPLC; ISTD).
Data of exo-isomer: IR (film): 2984, 1734, 1448, 1370, 1343, 1315, 1277, 1217, 1098, 1047, 1019, 907, 874, 808, 722, 704 cm -1; MS (EI, 70 eV): 139, 123, 94, 81, 68, 55, 41, 39, 29 m/z.
Data of undo-isomer: IR (film): 2984, 1736, 1451, 1370, 1337,1320,1304, 1194, 1131, 1095, 1055, 1025, 905, 855, 795, 712, 702 cm -1; MS (EI, 70 eV): 139, 123, 99, 95, 81, 68, 55, 43, 41,39, 29 m/z.
Example 2:
Preparation of (lS,2R,4S)-7-oxa-bicyclo[2.2.1]hept-5-ene-exo-2-carboxylic acid ethyl ester
507.5 g (2.77 mol) of a 92:8 exo/endo-mixture of raceme 7-oxa-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid ethyl ester was emulsified in 5.7 1100 mM potassium chloride, 3 mM potassium phosphate buffer pH 7 and 3.71 of octane ('Octane Fraction', Fluka 74830) by vigorous stirring. The emulsion was cooled to 1°C and the pH adjusted to 7.5 with IN NaOH solution. After addition of 0.75 MU of Charisma L-2 (Roche Diagnostics) the pH

was maintained at 7.5 under vigorous stirring at 1°C by the controlled addition (pH-stat) of 2.0 N NaOH-solution. After a total consumption of 930 ml 2.0 N NaOH-solution (corresponds to ca. 67% conversion with respect to the exam-isomer) after 10.6 h the reaction mixture was extracted with 3x81 dichloromethane (the first time the emulsion was passed through a bed of 500 g dicalite filter aid in order to enhance phase separation; the solvent for the second extraction step was passed through the filter bfed prior to use). The combined organic phases were dried on sodium sulfate, evaporated and dried on a high vacuum to give 160.5 g of a brownish oil. According to GC the title compound (93% eel) contained 20.5% of the endo-isomer, which was mostly removed from the mixture by distillation at 82°C-86°C / 3 mbar.
Data of exo-isomer: IR (film): 2984, 1734, 1448, 1370, 1343, 1315, 1277, 1217, 1098, 1047, 1019, 907, 874, 808, 722, 704 cm -1; MS (EI, 70 eV): 139, 123, 94, 81, 68, 55, 41, 39, 29 m/z.
Example 3:
Preparation of (lS,2S,4R,5R,6R)-3-(diethoxyphosphoryl)-8-oxa-3-aza-tricyclo[3.2.1.0 2,4]octane-6-carboxylic acid ethyl ester
A solution of 32.3 g (192 mmol) of (lS,2R,4S)-7-oxa-bicyclo[2.2.1]hept-5-ene-exo-2-carboxylic acid ethyl ester and 48.4 g (167 mmol) diphenylphosphoryl azide in 32 ml of toluene was stirred at 70°C for 18 h. Then 260 ml of ethanol were added, the mixture was cooled to 3°C and 150 ml (403 mmol) of 21% sodium ethyl ate solution were added during 15 min, allowing the mixture to reach room temperature. The mixture was stirred for 30 min at room temperature, then poured on a solution of 650 g of crushed ice in 650 ml of brine. The aqueous phase was extracted twice with 650 ml of ethyl acetate, the combined organic phases were dried over sodium sulfate, filtered and evaporated to give 64.8 g of crude product, which was subsequently chromatographer over silica gel with a 9:1 mixture of ethyl acetate and dioxin as the element, yielding 32.5 g (53%) of the product as an oil. Purity: 99% (ISTD).
IR (film): 3741, 2983, 2908,1735,1479, 1445,1393,1369, 1356, 1299, 1265, 1184, 1097, 1042, 983, 925, 897, 864, 833, 800, 740, 673 cm '; MS (EI, 70 eV): 320 (MH+), 290, 274, 262, 246, 234, 219, 191, 163,109, 91, 81, 65, 55, 39 m/z.
Example 4:
Preparation of (lS,5S,6S)-7-(diethoxyphosphoryl)-5-hydroxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester
A solution of 64.1 g (197 mmol) of (lS,2S,4R,5R,6R)-3-(diethoxyphosphoryl)-8-oxa-3-aza-tricyclo[3.2.1.0 2,4]octane- 6-carboxylic acid ethyl ester in 320 ml of THF was cooled to -65°C. Then 148 ml (296mmol) of 2 M sodium-bis-(trimethylsilyl)-amide in THF were added dropwise during 20 min, maintaining the temperature at below -60°C. The mixture was stirred at -60°C for 5 h, then 1.20 1 of ammonium chloride solution were added to the cold mixture, allowing it to reach 0°C after completed addition. 110 ml of water were added to the suspension to give a clear solution, which was stirred for 30 min while reaching room temperature. The solution was extracted with 1.60 1 of ethyl acetate, and the organic layer was washed with 60 ml of saturated sodium bicarbonate, dried over sodium sulfate, filtered and evaporated to give 57.1 g (91%) of product as an oil. Purity: 94% (ISTD). Optical rotation of further purified material: [a]D2o = -37.7°(c=l, EtOH).
IR (film): 3381, 2983, 2910,1712, 1647, 1446, 1393,1258, 1213, 1165, 1136,1096, 1028, 960, 932, 882, 848, 821, 801, 771, 748, 707, 655 cm'; MS (EI, 70eV): 319 (M+), 301, 290, 273, 262, 246, 234, 216, 202, 188, 174, 165, 137, 119,109, 99, 91, 81, 65, 53, 45 m/e.
Example 5:

Preparation of (3R,4S,5S)-4-(diethoxyphosphorylainino)-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-1-enecarboxylic acid ethyl ester
>
A solution of 25.13 g (78.7 mmol) of (lS,5S,6S)-7-(diethoxyphosphoryl)-5-hydroxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester and 9.61 g (94.4 mmol) of triethylamine in 250 ml of ethyl acetate was cooled to 0°C. 10.0 g (94.4 mmol) of methanesulfonic acid chloride were added dropwise during 10 min, maintaining the temperature below 10°C. After completed addition, the mixture was allowed to reach room temperature during 20 min, and the triethylamine hydro-chloride precipitate was filtered off and washed in several portions with a total of 75 ml of ethyl acetate. The combined filtrates were evaporated to give 35.1 g of a brownish oil, which was sub-squinty dissolved in 75 ml of dichloromethane. 220 ml (2.03 mol) of 3-pentanol were added, the mixture was cooled to 0°C, and 14.8 ml (118 mmol) of BF3*OEt2 were added during 10 min, maintaining the temperature at below 4°C. After completed addition, the mixture was stirred for 1.5 h at room temperature. The crude reaction mixture was evaporated at 30°C (removal of excess of 3-pentanol), and the resulting oil was partitioned between 500 ml of ethyl acetate and 250 ml of saturated sodium bicarbonate solution. The organic layer was washed with 20 ml of brine, dried over sodium sulfate, filtered and evaporated to give 36.4 g of a brownish solid.
Purification: 36.3 g of above crude product was taken up in 240 ml of ethyl acetate and heated to 60°C to give a clear solution. The solution was allowed to gradually cool to room temperature during 2 h, being seeded with product crystals at 50°C. The resulting suspension was stirred for 1 h at room temperature, filtered, washed portionwise with a total of 35 ml of ethyl acetate, and dried at 45°C / 5 mbar for 30 min to give a first portion of 15.67 g product as white crystals. The combined mother liquor and washings were evaporated, taken up in a mobster 50 ml of ethyl acetate and 25 ml of n-heptane and heated to 70°C. The mixture was allowed to cool to room temperature during 1.5 h, being seeded with product crystals at 50°C. The suspension was stirred for 15 min at room temperature and filtered. The residue was washed with a mixture of 7.5 ml of ethyl acetate and 2.5 ml of n-heptane and dried at 45°C / 5 mbar for 45 min to give a second portion of 8.28 g product as white crystals. Both product portions were combined to give 23.95 g (63%) product.

m.p. 140.5 - 141.0°C. Purity: 95o/o (ISTD). Optical rotation of further purified material: [a]D2o = -26.5°(c=l,EtOH).
IR (film): 3210, 2925, 2854, 1720, 1663, 1466, 1351,1286, 1252, 122],i 1175, 1156. 1142, i 1107, 1070, 1040, 966, 915, 895, 838, 811, 782. 748, 732 cm'; MS (Ell 70 eV): 486 (M+), 416, 398, 320, 302. 286, 274. 246 m/e.
Example 6:
Preparation of (3R.4S.5S)-4-amino-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-1-enecarboxylic acid ethyl ester hydrochloride
A solution of 22.07 g (41.4 mmol) of (3R.4S.5S)-4-(diethoxyphosphorylamino)-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-l-enecarboxylic acid ethyl ester in 90 ml of ethanol was cooled to 0°C. 22 ml (395 mmol) of 96% sulfuric acid were added dropwise during 25 min. maintaining the temperature at below 20°C. After completed addition, the mixture was stirred for 22 h at 70°C, then cooled to 0° and poured on an ice cold mixture of 1.0 1 of ethyl acetate and 1.01 of 10% (w/v) sodium hydroxide solution. After extraction, the phases were separated and the organic phase was washed with 280 ml of water, dried over sodium sulfate, filtered and evaporated to give 14,9 g of crude product. This material was taken up in 90 ml of tert.-butyl methyl ester, the suspension heated to 50°C to give a clear, brownish solution, and cooled to 10°C, where 30 ml of 4M HCl in ethanol were added, maintaining the temperature at below 20°C. After about 1 minute the product started to precipitate. The thick suspension was diluted with 50 ml of n-hexane and stirred for 15 min at room temperature. The precipitate was filtered off and dried at 40°C / 3 mbar for 30 min to give 11.09 g ( 63%) of product as white crystals.

IR (film): 3233, 2923, 2853. 2687, 2579, 1989, 1717, 1654, 1586, 1487, 1464, 1357,1340, 1266, 1225, 1177, 1067, 1021, 973, 940, 906, 885, 830, 747, 729 cm"'.
Example 7:
Preparation of (3R,4R,5S)-5-allylamino-4-amino-3-(l-ethyl-propoxyl-cydohex-l-enecarboxylic acid ethyl ester
A solution of 6.95 g (19.9 mmol) of (3R,4S,5S)-4-amino-3-(l-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-l-enecarboxylic acid ethyl ester hydrochloride and 6.1 ml (79. 6 mmol) of allylamine in 82 ml of tert.-butyl methyl ester was sealed in a pressure vessel under argon and heated to 110°C, resulting in a 4 bar internal pressure. After 20 h the mixture was cooled to room temperature and partitioned between 30 ml of tert.-but\'l methyl ester and 120 ml of saturated sodium bicarbonate solution. The aqueous phase was extracted with 50 ml tert.-butyl methyl ester, and the combined organic phases were dried over sodium sulfate, filtered and evaporated to give 5.90 g (96%) of product as a slightly brownish oil. Purity: 77% (ISTD).
IR(film): 3274, 3084, 2925, 2853, 1721, 1645, 1556, 1457, 1373, 1318, 1249, 1185, 1130, 1087, 1057, 1037, 995, 938, 770, 736; MS (70 eV): 353 (M+), 296, 283, 265, 226 m/e.
Example 8:
Preparation of (3R,4R,5S)-4-acetylamino-5-allylamino-3-(l-ethyl-propoxy)-cyclohex-1-enecarboxylic acid ethyl ester

In a 414-necked round bottom flask equipped with a thermometer, a mechanical stirrer, a Claisen condenser and an inert gas supply 278.0 g of (3R,4R,5S)-5-aIlylamino-4-amino-3-(l-ethyl-propoxy)-cyclohex-l-enecarboxylic acid ethyl ester obtained according to (c ) were dissolved at room temperature with stirring under argon in 2800 ml of tert.-butyl methyl ether. From the red solution 1400 ml of tert.-butyl methyl ether were distilled. Again 1400 ml of tert.-butyl methyl ether were added and distilled off. The red solution was cooled to 0-5°C and treated with 512 ml of acetic acid (9.0 mol) whereby the temperature rose to about 23°C. After cooling to 0°C-5°C 58.1 ml of methanesulfonic acid (d= 1.482, 0.90 mol) were added dropwise in the course of 27 min followed by 84.7 ml of acetic anhydride (d=1.08, 0.90 mol) added dropwise in the course of 40 min keeping the temperature in the range of 0°C to 5°C. The brown reaction mixture was stirred without cooling for 14 h then treated with vigorous stirring with 1400 ml of water (deionized) for 30 min and the brown organic phase was extracted with 450 ml of IM aqueous methanesulfonic acid. The combined aqueous phases (pH=1.6) were treated with stirring with about 694 ml of 50% aqueous potassium hydroxide until pH=10.0 was reached, keeping the temperature in the range of 10 to 25°C. The brown, turbid mixture was extracted first with 1000 ml then with 400 ml, in total with 1400 ml of tert.-butyl methyl ether, the combined organic extracts were stirred over 32 g of charcoal and filtered. The filter cake was washed with about 200 ml tert.-butyl methyl ether and the combined filtrates were evaporated in a rotary evaporator at 47°C / 380 to 10 mbar to yield 285.4 g of brown-red, amorphous crystals which were dissolved with stirring in a mixture of 570 ml of tert.-butyl methyl ether and 285 ml of n-hexane at 50°C. The brown solution was cooled in 45 min with stirring to -20°C to -25°C and stirred for 5 h whereby brown crystals precipitated. The suspension was filtered over a pre-cooled (-20°C) glass filter funnel and the filter cake was washed with a pre-cooled (-20°C) mixture of 285 ml of tert.-but>'l methyl ether and 143 ml of n-hexane and dried in a rotary evaporator at 48°C Example 9:
Preparation of (3R,4R,5S)-4-acetylamino-5-amino-3-(l-ethyl-propoxy)-cyclohex-1 -enecarboxylic acid ethyl ester
In a 11 4-necked round bottom flask equipped with a thermometer, a mechanical stirrer, a reflux condenser and an inert gas supply 176.2 g of (3R,4R,5S)-4-acetylamino-5-

aIIylamino-3-(l-ethyl-propoxy)-cyclohex-l-enecarboxylic acid ethyl ester obtained according to example 8 and 30.0 ml of ethanolamine (d=1.015, 0.54 mol) were dissolved at room temperature in 880 ml of ethanol and treated with 17.6 g of 10% palladium on charcoal. The black suspension was heated to reflux for 3 h, cooled to room temperature and filtered. The filter cake was washed with 100 ml of ethanol and the combined filtrates
t
f
were evaporated in a rotary evaporator at 50°C / (3R,4R,5S)-4-acetylamino-5-amino-3-(l-ethyl-propoxy)-cyclohex-l-enecarboxylicacid ethyl ester as white crystals; m.p. 205-207°C, decomposition.

WE CLAIM;
1. A process for the preparation of a 4,5-diamino Chichimec acid derivative of formula

and phamiaceutical acceptable addition salts thereof wherein
R1 is an optionally substituted alkyl group having 1 to 2 carbon atoms,
R2 is an alkyl group having 1 to 20 carbon atoms and
R3 and R4, independent of each other are H or a subsistent of an amino group,
with the proviso that not both R3 and R4 are H, comprising
step a) • furan is reacted in a known manner with an acrylic acid

wherein R2 is as above and R5 is an aide residue then, in

wherein R2 and R5 are as defined herein above,
step e) a subsistent R6 is introduced in a known manner in the free OH-
monition

wherein R1,R2 and R6 are as defined herein above and converting said 4-ainino cyclohexene derivative of formula (VII) to the 4,5-diamino Chichimec acid derivatives of formula (I) and phamiaceutical acceptable salts thereof in a known manner and isolating the said compound I in a known manner.
2. The process as claimed in claim 1 wherein said compound of formula VII is converted into compounds of formula I by transformation into an ranitidine of formula
wherein R' and R^ are defined herein above, by reacting with a tertiary amine and converting said ranitidine of formula VIII to the azide of formula

wherein R1 R2, R3 and R4 are as defined herein above in a known manner followed by reducing the said compound of formula DC in a known manner and converting the same to the pharmaceutically acceptable addition salt in a known manner.
V . %r hi■■--'

The process as claimed in claim 1 wherein the transformation of 4-amino cyclohexene derivative of the formula VII into a 5-N-substituted-4,5-diamino shikimic acid derivative of formula

wherein R^ and R' are as herein defined above and R1and R2, independent of each other are H or a substituent of an amino group, with the proviso that not bola R7 and R8 are H by reacting with an amine of tbnnula R7NHR8 acieration of the amino group in position 4 in a known manner and releasing the amino group in position 5 in a known manner and, if necessary, the formation of the phamiaceutical acceptable addition salt by known metalloids.
4. The process as claimed in claim I, wherein step (a) is performed in tlie presence. of a Lewis acid.
5. The process as claimed in claim 4, wherein the Lewis acid is zinc chloride used in stoechiometric amounts relating to the bicyclo compound of formula (III).
6. The process as claimed in claims 1 to 3, wherein separation of the 2R-e.xo isomer of the bicyclo compound of formula (III) is effected by means of a lipase of the EC class 3.1.1.3 or a lipoprotein lipase of the EC class 3.1.1.34, both lipase being capable to specifically hydrolyze the 2S-exo isomer of the bicyclo compound of formula (III) only, and by separation of the 2R-exo isomer from the end isomers by subsequent distillation.
■/ ^^TT^
■ 5 FEB ZQ03

7. The process as claimed in claim 6, wherein said lipase is of the genus Candida antarctica.
8. The process as claimed in claims 1 to 7, wherein the a2ide used in step (c) to form the aerodyne of formula (IV) is diphenyl phosphoric azide.
9. The process as claimed in claims 1 to 8, wherein the elimination ring opening in step (d) is effected in the presence of a strong organic base such as herein described.
10. The process as claimed in claim 9, wherein said strong organic base is an alkali-bis-(trimethylsilyi) amide.
11. The process as claimed in claim 1, wherein step (e) comprises the transformation of the OH-group into a sulfuric acid ester.
12. The process as claimed in claim 11, wherein a methanesulfonic acid ester is formed.
13. The process as claimed in claims 1 to 12, wherein the removal of R5 in step (f)
is carried out under strong acidic conditions. - - ^
14. A process for the preparation of a 4,5-diamino shikimic acid derivative
substantially as herein described and exemplified.

Documents:

0153-mas-2001 abstract.jpg

0153-mas-2001 abstract.pdf

0153-mas-2001 claims.pdf

0153-mas-2001 correspondence-others.pdf

0153-mas-2001 correspondence-po.pdf

0153-mas-2001 description(complete).pdf

0153-mas-2001 form-1.pdf

0153-mas-2001 form-26.pdf

0153-mas-2001 form-3.pdf

0153-mas-2001 form-5.pdf

0153-mas-2001 form-9.pdf

0153-mas-2001 others.pdf

0153-mas-2001 petition.pdf

153-mas-2001.jpg

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Patent Number

192890

Indian Patent Application Number

153/MAS/2001

PG Journal Number

30/2009

Publication Date

24-Jul-2009

Grant Date

18-Apr-2005

Date of Filing

20-Feb-2001

Name of Patentee

F HOFFMANN-LA ROCHE AG

Applicant Address

124 GERNZACHERSTRASSE, CH-4070 BASLE

Inventors:

#	Inventor's Name	Inventor's Address
1	STEFAN ABRECHT	4 KIRCHSTRASSE, CH-4202 DUGGINGEN
2	MARTIN KARPF	7 LANDERERSTRASSE, CH-4153 REINACH
3	RENETRUSSARDI	2 SALINENSTRASSE, CH-4127 BIRSFELDEN.
4	BEAT WIRZ	4 WIEDENWEG CH-4153 REINACH

PCT International Classification Number

C07C229/30

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	00103673.0	2000-02-22	EUROPEAN UNION