|Title of Invention||
IMPROVED PROCESS FOR PREPARATION OF TRIAZOL- BENZODIAZEPINE DERIVATIVES
|Abstract||An improved process for preparation of triazol-Benzodiazepine derivatives like Alprazolam, Triazolam, brotizolam and Etizolam comprises a cyclization reaction of compound formula –B in toluene with catalytic amount of aliphatic or aromatic sulphonic acid or sulphuric acid to obtain compound formula (A) : X is hydrogen or halogen.|
|Full Text||FORM 2
THE PATENT ACT 1970
(39 of 1970)
The Patents Rules, 2003
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Improved process for preparation of Triazoi- Benzodiazepine derivatives"
2. APPLICANT (S)
(a) NAME: Centaur chemicals Pvt. ltd
(b) NATIONALITY: An Indian Company incorporated under the Indian Companies ACT 1956
Centaur chemicals Pvt. ltd.
Centaur House, shanti Nagar,Vakola,
Santacruz (e) Mumbai 400055.
Tel No. 66499144
Fax No. 66499108/112
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to
Improved process for preparation of Triazol- Benzodiazepine derivatives.
Field of invention:
This invention mainly relates to the improved process for preparation of pharmaceutically active triazol-benzodiazepine derivatives such as Alprazolam, Triazolam, Brotizolam and Etizolam etc. Theses pharmaceutically active agents are short acting drug in the benzodiazepine class used to treat anxiety disorder and as an adjunctive treatment for depression. The general chemical structure of triazol-benzodiazepine derivatives is depicted by following formula -A which has been obtained from Formula B by cyclization process:
spiral line indicates that attaching to benzodiazepine nucleus of the side.
X is hydrogen or halogen, i.e. chlorine, fluorine, bromine or iodine.
Background of Invention:
Triazole-benzodiazepine derivatives such as Alprazolam, Triazolam, Brotizolam and Etizolam etc. its therapeutic indication is anxiety disorder and adjunctive treatment for depression. The general structural scheme for preparation for Alprazolam, Triazolam, Brotizolam and Etizolam is represent as follows:
R and X are defined above.
From the general scheme as given above its synthesis preparation has a common strategy wherein, triazol ring formation is a common step. The benzodiazepine moiety (Formula-a) required for synthesis can be prepared from corresponding suitable benzophenone derivatives which is commonly described in the literature. The synthesis of triazol-benzodiazepine involves a common step of cyclization & formation of triazol ring from acetyl hydrazone derivatives (Formula-b) derived from different benzodiazepine. The formation of acetyl hydrazone derivatives and its cyclization forms a common synthetic schemes in various triazol-benzodiazepine such as Alprazolam, Triazolam, Brotizolam and Etizolam etc. The common strategy involved in triazol-benzodiazepine is described in above scheme.
The present invention relates to the convenient process of cyclization of acetyl hydrazone derivatives (Formula-c)
The available literature reports describe various strategies for the formation of benzodiazepine-triazol moieties in patent US- 3987052 by Jackson Hester et.al.
l,3-dihydro-5-phenyl-2H-l,4-benzodiazepine -2-thione of formula (I) in ethanol when condensed with acetyl hydrazide (Formula-II) at temperature 60-120°C for 24 hours obtained a crude mixture of corresponding 2-(2-acetyl hydrazino)-5-phenyl-3H-l,4-benzodiazepine (formula-Ill) and the corresponding 8-chloro-l- methyl -6-phenyl-4H-s -triazolo [4,3 -I] [1,4] benzodiazepine formula (IV) which on further purification by conventional methods like, extraction or chromatography obtained the title compound in yield 47.7%.
From commercial point of view, above said preparation is tedious and lengthy as well as expensive due to low yield as it concomitantly formed compound formula of (III).
In our preferred embodiment, intermediate for alprazolam 2- (2-acetyl hydrazino)-7-chloro-5-phenyl-2H-l,4 benzodiazepine referred as acetyl hydrazone cyclizes in toluene at reflux temperature in presence of p-toluene sulphonic acid for 10-12 hours, to obtain 8-chloro-l-methyl -6-phenyl -4H-s-trizolo [4 3-1] [1,4] benzodiazepine referred as Alprazolam in a good yield without formation of side products.
According to US 1971-129273 A Hester, Jackson Boling, Jr et all, 7-Chloro-l,3-dihydro-5-phenyl-2H-l,4-benzodiazepine-2-thione was treated with AcNHNH2 to give 2-(2-acetylhydrazino)-7-chloro-5-phenyl-3H-l,4-benzodiazepine, which was cyclized by heating under N2 at 250 °C to give the title compd. (I) Alprazolam.
From above prior art the said invention is not compatible for large scale preparation because of utility point of view.
In our preferred embodiment no such types of temperature parameter used for the cyclization purpose to obtain a title compound.
According to patent HR-2001000081 A, Alprazolam was prepared by reaction of hydrazide compound with tri-ethyl ortho acetate in presence of catalyst.
From above said preparation, catalyst used for cyclization purpose is expensive as well as not commercially available, so as taking into account for large scale preparation process is not feasible because of for high manufacturing cost and non availability of the catalyst commercially.
In our said invention, commercially available solvent like toluene and catalyst like aromatic sulphonic acid is used to exert good yield with purity and also process is cost effective due to simple and commercially available catalyst.
In patent DE- 3413709 A, The title compound I (Rl = H, CI-3 alkyl; R2 - R5 = H, Cl-3 alkyl, halo) were prepared by mesylating ales. II (R = H) and cyclizing the product II (R = SO2Me) with aq. NH4OH in Cl-3 alkanol. Mesylating II (R, R2 - R4 = H, Rl = Me, R5 = CI) in DMF, THF, and NEt3 with MeSO2Cl-THF at -10°C over 30 min, then stirring 30 min, filtering, and treating the filtrate [contg. II (R = S02Me)] with aq. NH4OH-MeOH gave alprazolam (I, Rl = Me, R2 - R4 = H, R5 = CI).
From above said process, numbers of operations are more to obtain the title compound with critical parameter and reagents like methane sulphonyl chloride -tetra hydro furan (THF) at -10 °C.
In our preferred embodiment, no such type of reagents and critical reaction parameters are used, also solvent used as reaction medium is recovered in greater extent after the completion of reaction which has been briefly disclosed below and elaborately explained in forgoing example.
Object of invention:
The main object of said invention is to provide a commercially suitable process which involves less number of operations and use nonhazardous reagents or solvents for the preparation of trizol-Benzodiazepine derivatives like Alprazolam, Triazolam, Brotizolam and Etizolam. Other feature of the invention is to provide cost effectiveness and environment friendly process over the existing prior arts.
Summery of invention:
This invention mainly directed to industrially applicable and commercially feasible process for the preparation of triazol-benzodiazepine derivatives such as Alprazolam ,Triazolam,Brotizolam and Etizolam etc. The improved process is carried out under mild condition and without use of highly toxic reagents.
This method further provides substantial benefits relative to previously used or suggested production methods. For example, the starting materials, intermediates, liquid media, and catalysts used are relatively easy to handle and to dispose off, if necessary. Importantly, the present method Provides high yields of the desired product so that substantial process efficiencies are achieved.
The present invention describes the preparations of triazol-benzodiazapine derivatives such as, Alprazolam, Triazolam, Brotizolam and Etizolam involve the following common synthetic step:
R and X are defined above.
Detail description of Invention:
This improved process for preparation of triazole-benzodiazapine derivatives carried out in single step which has been depicted as follow:
R and X are defined above.
Charged acetyl hydrazone referred as formula -B (1.0 mole) in toluene (1-50 parts) in RB flask. Distilled out toluene partially at 110-112°C. Cooled the reaction mixture to 90-95°C and charged catalytic amount of aliphatic or aromatic sulphonic acid, acidic resins or sulphuric acid. Refluxed the reaction mixture at 105-110°C for 1-20 hours, cooled to 25-30°C. The reaction mass was further cooled to 0-15°C and stirred at same temperature for 4-5 hrs. The solids precipitated were filtered and washed with cold toluene and finally purified by single or mixture of solvents like methanol, ethanol, isopropanol, t-butanol, toluene and ethyl acetate.
The same process carried out as disclosed in said process for Alprazolam, Triazolam, Brotizolam and Etizolam this has been well depicted in forgoing Example 1.
Following example is offered to provide the general state of preparation for Alprazolam,Triazolam,Brotizolam and Etizolam, the person skill in the art with sufficiently clear
and complete explanation of this invention, but should not consider as a limitation to the essential aspect of the object thereof, as they have been explained in below.
R and X are defined above.
General Preparation of triazole-benzodiazepine derivatives:
Charged acetyl hydrazone (1.0) referred as formula -B and toluene (1-50 parts.) in RB flask. Distilled out toluene partially at 110-112°C. Cooled the reaction mixture to 90-95°C and add catalytic amount of aliphatic or aromatic sulphonic acid or acidic resins or sulphuric acid in a proportion of 0.1 to 1.0 mole percent. Refluxed the reaction mixture at 105-110°C for 10-12 hrs with Dean-Stark apparatus for water removal. At the end of the reaction (as indicated by TLC), reaction mixture was cooled to 25-30°C. The reaction mass was further cooled to 10-15°C and stirred at same temperature for 4-5 hrs. The solids precipitated were filtered and washed with cold toluene; Title compound (crude) thus obtained was purified using methanol/ethanol/ isopropanol/1-butanol/ toluene & ethyl acetate
Yield: 75-80 %.
1) An improved process for preparation of triazol-benzodiazepine derivatives of formula-A comprises:
X - is hydrogen or halogen i.e. chlorine, fluorine ,bromine, iodine.
a) compound formula-B:
R and X are as defined above.
Cyclizing in presence of aliphatic or aromatic sulphonic acid or acidic resins or sulphuric acid as catalyst and toluene as reaction medium to obtain compound formula -A.
b)The process as claimed in claim 1 ,wherein reaction mass (after completion of reaction) was cooled to 25-30 °C further cooled to 10-15 °C to obtain a solid of compound formula -A.
2) The process as claimed in claim 1 , wherein the molar ratio of catalyst to acetyl hydrazone (Formula-B; when X is hydrogen or halogen) is at least 1: 100 proportions.
3) The process as claimed in claim 1, wherein said cyclization of formula-B carried out at temperature 100 -110 °C for 10-12 hours.
4) The process as claimed in claim 1, wherein said solvent in which cyclization carried out in
toluene at its boiling temperature.
5) The process as claimed in claim 1, wherein said reaction mass obtained after completion of
reaction then cool to 25-30 °C further cool to 10-15 °C and stirred at same temperature for 4-5
hours to obtain a solid of Formula -A (Alprazolam,Triazolam,Brotizolam and Etizolam)
6) The process as claimed in claim 1, wherein product obtained from said cyclizazation reaction of formula-B treated with aliphatic solvent like , methanol, ethanol or ester like solvent ethyl acetate or aromatic solvent like toluene to obtain a pure form of formula- A .
7) The process as claimed in claim 1 to 6 ,wherein said process is used in the manufacture of Alprazolam, Triazolam, Brotizolam and Etizolam etc. with 8) An improved process for synthesis of Alprazolam , Triazolam ,Brotizolam and Etizolam as substantially described herein with reference to the above said example-1.
An improved process for preparation of triazol-Benzodiazepine derivatives like Alprazolam, Triazolam, brotizolam and Etizolam comprises a cyclization reaction of compound formula -B in toluene with catalytic amount of aliphatic or aromatic sulphonic acid or sulphuric acid to obtain compound formula (A):
Wherein: R is,
X is hydrogen or halogen.
|Indian Patent Application Number||1951/MUM/2007|
|PG Journal Number||07/2013|
|Date of Filing||03-Oct-2007|
|Name of Patentee||CENTAUR CHEMICALS PVT. LTD.|
|Applicant Address||CENTAUR HOUSE, SHANTI NAGAR, VAKOLA, SANTACRUZ (E), MUMBAI.|
|PCT International Classification Number||C07D495/14|
|PCT International Application Number||N/A|
|PCT International Filing date|