Organocatalytic Enantioselective Synthesis of Nitrogen-Substituted Dihydropyran-2-ones, a Key Synthetic Intermediate of 1β-Methylcarbapenems

Organocatalytic enantioselective cycloadditions providing nitrogen-substituted dihydropyran-2-ones were developed in two catalytic systems. The (3R,4R)-product was a versatile intermediate in the synthesis of 1 beta-methylcarbapenem antibiotics.