A new synthetic route to 3,4-dihydro-2H-1,4-thiazines

Abstract

3,4-Dihydro-2H-1,4-thiazine-6-carboxylates have been synthesised by reaction of 2-mercaptoethylamine with 2,3-dibromoacrylic esters. Of particular value for the preparation of analogues of the cephalosporins is the direct conversion of 2-mercaptoethylamine into 3,4-dihydro-2H-1,4-thiazine-5-carboxylic acids containing 6-carboxylate groups.