Synthesis of a Highly Reactive 1,1-Dicyanomethylene-1- dethiacephalosporin.

Synthesis of the 1,1-dicyanomethylene-1-dethiacephalosporin 1a is described. Substitution of the dicyanomethylene moiety for sulfur at position 1 of the cephem nucleus resulted in a highly reactive β-lactam antibacterial.