Chiral 1- beta -methyl-carbapenem intermediates

摘要

A multistep process is described for selectively obtaining 1- beta -methylcarbapenem intermediates in high overall yield. The desired 1- beta -methyl chirality is obtained through the hydrogenation of certain bicyclic beta -lactam ring structures containing an exocyclic methylene double bond alpha to the beta -lactam ring, in the presence of a metallic nickel hydrogenation catalyst. The hydrogenation results in a mixture of alpha - and beta -methyl isomers having a high beta / alpha epimeric molar ratio. New 1- beta -methylcarbapenem intermediates containing the exocyclic double bond are also described.