Diastereoselective Synthesis of syn‐β‐Lactams Using Rh‐Catalyzed Reductive Mannich‐Type Reaction of α,β‐Unsaturated Esters.

Reaction conditions are optimized for the Rh-hydride complex catalyzed reaction of α,β-unsaturated esters with imines to give syn-3,4-disubstituted β-lactams.