Mannich Reactions of Cephalosporin Sulphoxides and Sulphones with Imonium Salts. An Improved Synthesis of 2-Methylene-cephalosporins

Abstract

2-Methylenecephem-1-oxides (4) or -1,1-dioxides (6) can be very conveniently obtained through the use of dimethyl(methylene)imonium salts, which can be prepared in situ or in advance from bis(N,N-dimethylamino)methane (2) and a reactive acid derivative.