Process for preparation of 3-exomethylene cepham sulfoxide esters

Abstract

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.