FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
and
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10 and rule 13]
1. Title: A process for the preparation of (Z)-(6R, 7R)-3-(acetoxymethyl)-7-[2-(2-
amino-l,3-thiazol-4-yl)-2-methoxyiminoacetamido]-8-oxo-5-thia-l-azabicyclo [4,2,0]oct-2-en-2-carboxylic acid (Cefotaxime acid).
Applicant: Claris Lifesciences Limited,
Claris Corporate Headquarters, Nr.Parimal Crossing, Ellisbridge, Ahmedabad-380 006, Gujarat, India.

The following specification particularly describes the invention and the manner in
which it is to be performed.


DESCRIPTION
Field of Invention :
The present invention relates to an improved process for the production of (Z)-(6R, 7R)-3-(acetoxymethyl)-7-[2-(2-amino-l,3-thiazol-4-yl)-2-methoxyiminoacetamido]-8-oxo-5-thia _1-azabicyclo[4,2,0]oct-2-en-2-carboxylic acid (Cefotaxime acid). The synthesis of Cefotaxime acid comprises the condensation of S-(2-benzothiazoyl)-2-(2-amino-thiazol-4-yl)-2-methoxyimino thioacetate with 7-amino-3~acetoxymethyl-3-cephem-4- carboxylic acid in presence of aqueous organic solvent and organic base. Cefotaxime acid is subsequently isolated by organic acid.
BACKGROUND OF THE INVENTION
Cefotaxime is a third-generation cephalosporin antibiotics, it has broad-spectrum activity against both Gram-positive and Gram-negative organism.
The bactericidal activity of Cefotaxime works by inhibiting bacterial cell wall biosynthesis. Cefotaxime shows high affinity for penicillin-binding proteins (PBP) in the cell wall including PBP lb and PBP III. A positive feature of Cefotaxime is that it displays a resistance to penicillinases and is useful to treat infections that are resistant to penicillin derivatives. Cefotaxime has in vitro activity against a wide range of Gram-positive and Gram-negative organisms. Cefotaxime
2

should be administered by both Intravenous as well as Intramuscular route.
DESCRIPTION OF THE PRIOR ART
Cephalosporin antibiotics inhibit bacteria by interfering with the synthesis of essential structural components of the bacterial cell wall. They are considered as highly effective antibiotics with low toxicity and are used for treating a wide variety of bacterial infections. A number of cephalosporin derivatives have been discovered with increased potency and improved stability. Ochiai et al. US 4,098,888 described cephem compounds and processes for their preparation. Heymes et al. US 4,152,432 described 3~acetoxymethyl-7-(iminoacetamido) cephalosporonic acid derivatives, in particular Cefotaxime, and process for preparing the derivatives.
The "third-generation cephalosporins" generally consist of 3-methyl-3-cephem-4-carboxylic acid derivatives substituted in the 7f3-position by an a-(2-aminothiazol-4-yl)-a-hydroxyiminoacetamido group, in which the hydroxy group is free or substituted with an alkyl group, optionally substituted by a carboxy group, and substituted on the methyl group in the 3-position with the residue of a nucleophilic compound.
3

The above-mentioned third-generation cephalosporins have been described for the first time in the published German application DE 2,556,736 (corresponding to US 5,583,216).
US 4,767,852 discloses a process for the preparation of known 2-oxyiminoacetamido-3-cephem-4-carboxylic acid derivatives, including Cefotaxime and Ceftriaxone, by acylating 7-amino-3-cephem-4- carboxylic acid derivatives already substituted at the 7-position with 2- mercaptobenzothiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxyirninoacetate(MAEM). As the first step in the process disclosed in that patent, 7-amino-3-cephem-4-carboxylic acid (7-ACA) already suitably substituted at the 3-position is acylated at the 7-position using MAEM as the acylating agent. Thus MAEM has become the standard acylating agent for the preparation of cephalosporins having an oximino group and a 2-aminothiazolyl group in the 7-acylamido-side chain.
US 5,317,099 describes a process for the synthesis of J3-lactam derivatives such as Cefotaxime and Ceftriaxone in which silylated 7-ACA is acylated with acyloxyphosphonium chloride derivative of 2-(2-aminothiazol-4-yl)-2-syn-methoxyimino acetic acid, which in turn is prepared from triphenylphosphine (TPP), hexachloroethane or carbon tetrachloride and 2-(2-aminothiazol-4-yl)-2-syn-methoxyimino acetic acid. Since, TPP is used as reactant and hence the overall cost becomes high.
4

US 4,767,852 and US 5,003,073 disclose a process for the production of cephalosporin derivatives by acylating 7-amino-3-cephem-4-carboxylic acid (7-ACA) derivative with 2-mercaptobenzothiazolyI-(Z)-2-(2- aminothiazol-4-yl)-2-methoxyimino acetate (MAEM), using solvents such as chlorinated hydrocarbons, ethers or esters such as ethyl acetate or in a mixture of such solvent with water.
US 5,026,843 disclose a process for preparing Ceftriaxone disodium salt hemi-heptahydrate. As the first step in the process disclosed in that patent, 7-amino-3-{(2,5-dihydro-6-hydroxy-2-methyI-5-oxo-l,214-triazin-3-yl)thiomethyl}-3-cephem-4-carboxylic acid (7-ACT) already suitably substituted at the 3-position is acylated at the 1-position using 2-mercaptobenzothiazolyl-(Z)-2-(2- aminothiazol-4-yl)-2-methoxyimino acetate (MAEM) as the acylating agent.
US 5,037,988 describes a process for the production of cephalosporins, in particular Cefotaxime and Ceftriaxone, in which an activated form of an organic acid, i.e., 2-(2-aminothiazol-4-yl)-2-oxyiminoacetyl sulfitedialkylformiminium halide hydrohalide is coupled with a 7-amino-cephaIosporanic acid derivative. The compound of 2-(2-aminothiazol-4-yl)-2-oxyiminoacetyl sulfitedialkylformiminium halide hydrohalide was prepared by reacting 2-(2-aminothiazol-4-yl)-2-oxirnino acetic acid with dimethylforrniminium chloride chlorosulfite which in turn was
5

prepared by reacting approximately equimolar quantities of thionyl chloride and dimethylformamide at room temperature in specific solvents only like benzene or toluene and hence suffers from a limitation.
Object of the present invention is to over come the above said problem and provide a simple, very mild reaction condition, shorter time, and cost-effective method for preparation of Cefotaxime acid in
pure form.
SUMMARY OF THE INVENTION
The present invention relates to a simple, efficient and commercially feasible method for the production of a Cefotaxime acid. The process of the invention involves commercially cheaper and readily available raw materials and shorter reaction time and easy isolation process to obtain Cefotaxime acid in pure form.
It has now been found, and it constitutes the object of the present invention, that the reaction between 7-amino-3-cephem-4-carboxylic acid (7-ACA) and S~(2-benzothiazoyl)-2-(2-amino-thiazol-4-yl)-2-methoxyimino thioacetate (MAEM) may also be carried out in the presence of particular reagents and solvents, which allow the reaction to be performed in extremely mild ambient conditions. The use of the reagents and solvents in the process of the invention makes it possible to obtain Cefotaxime acid in a very pure
6

form and with very high yields.
The reaction is carried out in an aqueous solution at a temperature-20° to 30° C, in the presence of suitable organic solvents and organic base. Suitable organic solvent are selected from the group consisting of tetrahydrofuran, N,N dimethylaniiine and dimethyl acetamide, and mixtures thereof, and organic base is triethylamine.
The so formed salt of Cefotaxime is not isolated from the aqueous solution which contains it, the aqueous solution is directly treated with N.N-dibenzylethylenediamine diacetate and obtaining there from a practically quantitative precipitation of the N,N-dibenzylethylenediamine salt of Cefotaxime in a pure state.
The N,N-dibenzylethylenediamine salt of Cefotaxime is then made to react in the presence of suitable organic solvents such as, for example, aqueous acetone and triethylamine. The salt is than treated with p-toluene sulphonic acid to recover Cefotaxime acid in a pure state, and higher yields.
The embodiment provides the process of Cefotaxime acid. The process consist of the acylation of 7-Amino-3-cephem-4-carboxylic acid with S- (2-benzothiazolyl-2-(2- aminothiazol-4-yl)-2-methoxyimino thioacetate in presence of suitable organic solvent. After the compietion of reaction the aqueous layer from the mixture is
7

extracted with ethyl acetate. The aqueous solution is than treated with N.N-dibenzylethylenediamine for the Salt formation of (Z)-(6R, 7R)-3-(acetoxymethyl)-7-[2-(2-amino-l,3-thiazol-4-yl)-2-methoxyiminoacetamido]-8-oxo-5-thia-l-azabicyclo [4,2,0] oct-2-en-2-carboxylic acid (Cefotaxime acid). Isolation of the N,N-dibenzylethylenediamine salt of Cefotaxime acid with Chlorinated hydrocarbon solvent with constant stirring for overnight. After completion of the isolation N,N dibenzylethylenediamine salt of Cefotaxime acid filter and wash the salt with acetone. After the filtration and washing dry the salt.
The conversion of the N,N-dibenzylethylenediamine salt of Cefotaxime acid to Cefotaxime acid, make a suspension of N,N-dibenzylethylenediamine salt of Cefotaxime acid in acetone and water. Add triethylamine drop wise with constant stirring and add para-toluene sulphonic acid with constant stirring. Filter and dry the final product. Finally, (Z)-(6R, 7R)-3-(acetoxymethyl)-7-[2-(2-amino-l,3-thiazol-4-yl)-2-methoxyiminoacetamido]-8-oxo-5-thia-l-azabicycIo[4,2,0]oct-2-en-2-carboxyIic acid (Cefotaxime acid) is obtained in pure form.
DETAIL DESCRIPTION OF THE INVETNION
The present invention relates to a method for manufacture of (Z)-(6R, 7R)-3-(acetoxymethyl)-7-[2-(2-amino-lt3-thiazol-4-yl)-2-
8

methoxyiminoacetamido]-8-oxo-5-thia -l-azabicyclo[4,2,0]oct-2-en-2-carboxylic acid (Cefotaxime acid).The process of present invention comprises, 7-Amino-3-acetoxymethyl-3-cephem~4-carboxylic acid reacts with S- (2-benzothiazolyl)-2-(2-amino-thiazol-4-yl)-2-methoxyimino thioacetate in presence of dimethyl acetamide, tetrahydrofuran and organic base. 7-Amino~3~ acetoxymethyl-3-cephem-4-carboxylic acid and S- (2-benzothiazolyl)-2-(2-amino-thiazol-4-yl)-2-methoxyimino thioacetate suspended in a mixture of water, dimethyl acetamide, tetrahydrofuran, than cool the reaction mass between -20°C to 30°C. Add organic base drop wise with constant stirring within 10 min. to 20 min. and than stir the reaction mass for about 15 min. to 45 min. at same temperature. The organic base are triethylamine, 2,3-picoline, 2,4 -picoline, 1,4-dimethyl piperazine, N-ethylpiperidine, N-methyl morpholine, tri methyl aniline, pyridine, dimethyl amino pyridine, N-methyl piperidine, N-methyl pyridine, N-ethyl dimethyl aniline, diethyl amine, N-ethyldimethyl amine, diisopropyl ethyl amine, N,N-dimethyl aniline and tributyl amine. Compound other than S-(2-benzothiazoyl)-2-(2-amino-thiazol-4-yl)-2-methoxyimino thioacetate that can react with 7-Amino-3-acetoxymethyl-3-cephem-4-carboxylic acid to manufacture Cefotaxime acid are 2-mercapto-5-methyl-l,3,4-thiadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxyimino acetate or 2-mercapto-5-phenyl-lf3,4-oxadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxyimino acetate can be used. Monitor the reaction by high performance liquid chromatography
9

(HPLC) till the unreacted 7-amino~3-cephem-4- carboxylic acid less than 2 %. After completion of reaction, the mixture was extracted with ethyl acetate. Add N,N-dibenzylethylenediamine acetate to the aqueous solution with constant stirring. For isolalation of the N,N-dibenzylethylenediamine salt of Cefotaxime add dichloromethane drop wise with constant stirring. After complete isolation filter and wash the N,N-dibenzylethylenediamine salt of Cefotaxime with acetone and dry under the vacuum. N,N~dibenzylethylenediamine salt of Cefotaxime is treated with suitable acid in presences of aqueous solvent and triethylamine. Organic acids used for the isolation of Cefotaxime are p-toluene sulphonic acid monohydrate, methane sulfonic acid, benzene sulfonic acid and hydrochloric acid. The following examples are intended to be illustrative for the present invention and should not be taken as limiting the scope of this invention defined by the appended claim. Example^ 1
Part A: Preparation of N, N-dibenzylethylene diamine salt of Cefotaxime acid as follows:
A suspension of 5 gm 7-ACA & 8.04 gm MAEM in 55 ml water, 10.2 ml Dimethyl acetamide and 55 ml THF, was chilled to 10°C to 15°C and stir for 10 min. Add 3.26 ml of triethylamine were added with constant stirring at same temperature, raise temperature 10°C to 25°C gradually up to completion of reaction. After completion of Reaction, the mixture was extracted with 55 ml of Ethyl acetate. Stir for 10 min. and Collect aqueous layer and add 5 gm N, N dibenzylethylenediamine
10

acetate with const. Stirring at 20°C. Add 45 ml Dichloromethane dropwise with constant stirring. Stir at room temperature for overnight. After complete isolation, Filter and wash with Acetone. Suck dry and dry at 45°C under Vacuum.
Part B:
Take 2 gm above N, N-dibenzylethylenediamine salt of Cefotaxime and make suspension in 30 ml acetone and 5.2 ml water. Add 0.95 ml triethylamine drop wise with constant stirring. Stir and add 2.1 gm p-toluene sulphonic acid with stirring. Cooled it up to 10°C. Stir for 4 hours. Filter and dry it.
Example: 2
Part A-' Preparation of N, N-Dibenzylethylenediamine salt of Cefotaxime acid as follows:
A suspension of 10 gm 7-ACA & 16.08 gm MAEM in 110 ml water, 20.4 ml Dimethyl acetamide and 110 ml THF, was chilled to 10°C to 15°C and stir for 10 min. Add 5.13 ml of N-methyl morpholine were added with constant stirring at same temperature, raise temperature 10°C to 25°C gradually up to completion of reaction. After completion of Reaction, the mixture was extracted with 110 ml of Ethyl acetate. Stir for 10 min. and Collect aqueous layer and add 10 gm N, N dibenzylethylenediamine acetate with const. Stirring at 20°C. Add 90 ml dichloromethane drop wise with constant stirring. Stir at room
11

temperature for overnight. After complete isolation, Filter and wash with Acetone. Suck dry and dry at 45°C under Vacuum.
Part B:
Take 4 gm above N, N-dibenzylethylenediamine salt of Cefotaxime and make suspension in 60 ml acetone and 10.4 ml water. Add 1.9 ml triethylamine drop wise with constant stirring. Stir and add 4.2 gm p-toluene sulphonic acid with stirring. Cooled it up to 10°C. Stir for 4 hours. Filter and dry it.
12

claim,
1. A process of manufacturing a compound of (Z)-(6R, 7R)-3-(acetoxymethyl)-7- [2-(2-amino- l,3-thiazol-4-yl)-2-methoxyiminoacetamido]-8-oxo-5-thia -1-azabicyclo[4,2,0]oct-2-en-2-carboxylic acid the said method comprising:
a) acylating of a compound of the 7-Amino-3-cephem-4-carboxylic acid with S- (2-benzothiazolyl-2-(2-aminothiazol-4-yl)-2-methoxyimino thioacetate, presence of dimethylacetamide, tetrahydrofuran and organic base,'
b) extraction of Aqueous layer with ethylacetate;
c) treating the aqueous solution with N,N-dibenzylethylenediamine acetate to the aqueous solution in presence of dichloromethane to precipitate N,N-dibenzylethylenediamine salt of Cefotaxime;
d) N,N-dibenzylethylenediamine salt of Cefotaxime reacts with suitable acids in presence of acetone and triethylamine to give Cefotaxime acid.
2. The process of claim 1, wherein step (a), the said organic base are triethyl amine, 2,3-picoline, 2,4-picoline, 1,4-dimethyl piperazine, N-ethylpiperidine, N-methyl morpholine, trimethyl aniline, pyridine, dimethyl amino pyridine, N-methyl piperidine, N-methyl pyridine, N-ethyl dimethyl aniline, diethyl amine, N-
13

ethyldimethylamine, diisopropylethylamine, N,N-dimethylaniline and tributylamine.
3. The process of claim 2, wherein the organic base is
triethylamine.
4. The process of claim 1, wherein step (a), compound other than S-(2-benzothiazoyl)-2-(2-amino-thiazol-4-yl)-2-methoxyimino thioacetate are 2-mercapto-5-methyl-1,3,4-thiadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-methoxyimino acetate or 2-mercapto-5-phenyl-l,3,4-oxadiazolyl-(Z)-2-(2-aminothiazol-4-yl)-2-rnethoxyimino acetate can be used.
5. The process of claim 1, wherein step (d), suitable organic acids are para-toluene sulphonic acid monohydrate, methane sulfonic acid, benzene sulfonic acid and hydrochloric acid.
6. The process of claim 1, where in unreacted 7-Amino-3-cephem-4-carboxylic acid is not more than 2% by HPLC.
DATE and SIGNATURE
Date : 8th November 2008
Name : Chetan p. Majmudar
Designation: Director
Signature •
14