Lupin Laboratories Limited

Ramanathan Sankaran

Niranjan Lal Gupta

Sakina Sitabkhan

Sugata Chattejee

Tumma Hari Krishna

Shibu Varughese

A process for the stereospecific synthesis of keto-enol tautomeric mixture of p-nitrobenzyl (1R,6R,7R)-7-phenoxyacetamido-3-oxo-3-cepham-4-(R/S)-carboxylate-1-oxide and p-nitrobenzyl (1R,6R,7R)-7-phenoxyacetamido-3-hydroxy-3-cephem-4-carboxylate-1-oxide is described. These compounds are valuable intermediates for the synthesis of cephalosporin antibiotics e.g. cefaclor.

Process for sterospecific synthesis of keto-enol tautomeric mixture of p

A process for the stereospecific synthesis of keto-enol tautomeric mixture of p-nitrobenzyl(1R,6R,7R)-7-phenoxyacetamido-3-oxo-3-cepham-4-(R/S)-carboxyl ate-1-oxide and p-nitrobenzyl(1R,6R,7R)-7-phenoxyacetamido-3-hydroxy-3-cephem-4-carboxylat e-1-oxide is described. This process comprises

Process for the stereospecific synthesis of keto-enol tautomeric mixture

An improved method for the preparation of 2-chloro sulfinyl azetidin-4-one of the formula: ##STR1## wherein R is: hydrogen; C.sub.1 -C.sub.3 alkyl; halomethyl; cyanomethyl; phenyl; substituted phenyl; phenoxy, benzyloxy- or substituted benzyl; a group of the formula R.sub.2 --O--wherein R.sub.2 is t-butyl, 2,2,2-trichloroethyl, benzyl or substituted benzyl; a group of the formula R.sub.3 --(O).sub.n --CH.sub.2 wherein R.sub.3 is phenyl or substituted phenyl. The 2-chlorosulfinylazetidin-4-one is prepared by reacting a penicillin sulfoxide ester of the general formula ##STR2## wherein R and R.sub.1 have the meanings defined above with an N-chloro halogenating agent in an inert organic solvent. The reaction is carried out in the presence of an acid scavenging amount of a phosphate or hydrogen phosphate of an alkali metal, alkaline earth metal, ammonium, quaternary ammonium or mixtures thereof. These compounds find application as intermediates in the production of cefaclor which are powerful anti-bacterial compounds.

Method for the preparation of 2-chloro sulfinyl azetidinones

A process for the manufacture of 3-exomethylene cepham sulfoxide ester of the formula ##STR1## wherein R is hydrogen, C.sub.1 -C.sub.3 alkyl, halomethyl, phenyl, substituted phenyl cyanomethyl, phenoxy, benzyloxy or substituted benzyl with a substituent group such as that selected from halo, alkyl, alkoxy, protected hydroxy, nitro, cyano and trifiuoromethyl, a group of the formula R.sub.2 --0-- wherein R.sub.2 is t-butyl, 2,2,2-trichloro ethyl, benzyl or substituted benzyl; a group of the formula R.sub.3 --[0].sub.n --CH.sub.2, wherein R.sub.3 is phenyl or substituted phenyl with the substituent group selected from halo, alkyl, alkoxy, protected hydroxy, nitro, cyano, or 1,4-cyclohexadienyl, and n is 0 or 1; or a substituted arylalkyl group of formula R.sub.4 --CH where R.sub.4 has the same meaning as R.sub.3 defined above and W is a protected hydroxy or protected amino group; and R.sub.1 is a carboxylic acid protecting group such as that selected from the group consisting of C.sub.1 -C.sub.4 alkyl, 2,2,2-trihalo alkyl, benzyl, substituted benzyl such as para nitrobenzyl, phenacyl, halo substituted phenacyl and benzhydryl is disclosed. Such compound is prepared by reacting a chlorosulfinylazetidinone of the formula ##STR2## wherein R and R.sub.1 have the same meanings as defined above, with a Lewis Acid type Friedel-Crafts catalyst and a sulfur compound in an inert solvent under anhydrous condition. These compounds find application as an intermediate for the preparation of cephalosporin antibiotics.

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Bhopal, India

Ramanathan Sankaran