Process for preparing cepham intermediates

Abstract

There is described a process for producing exomethylene cepham intermediates useful in cephalosporin chemistry. The process comprises the preparation of a compound of the formula ##STR1## in which R.sup.1 is an amino group, a protected amino group, an acylamino group or a diacylamino group, R.sup.2 is hydrogen, C.sub.1-4 alkoxy or C.sub.1-4 alkylthio, R.sup.3 is hydrogen, a salt ion or an ester-forming group, and R.sup.4 is hydrogen or C.sub.1-3 alkyl, by reacting a compound of the formula ##STR2## in which Y is a bridging group of the formula ##STR3## Z is chloro, bromo or iodo, and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 have the above defined values, with a reagent providing cobalt I, under reducing conditions.

Dependencies are inferred from the claim text.