Synthesis and transformations of 3-vinylcephalosporins. Part 6. Reactions of cephalosporin phosphoranes with bifunctional carbonyl compounds
Abstract
Cephalosporin C-3-phosphoranes have been converted into the corresponding 3-alkenylcephems and novel tricyclic derivatives on treatment with different bifunctional carbonyl compounds. The effect of substituents on the product ratio has been examined. The stereoselectivity of the ringclosure is explained on the basis of theoretical considerations.