Synthesis of α-Methylene-β-lactams Enabled by Base-Promoted Intramolecular 1,2-Addition of N-Propiolamide and C-C Bond Migrating Cleavage of Aziridine.

A formal α-addition of N-propiolamide and 2-bromoacetate is reported for the synthesis of α-methylene-β-lactam in good yields. The transformation proceeds smoothly in the presence of K2CO3 as a base and KI as an additive. An excellent reaction scope is observed. A 2 mmol scaled synthesis of α-methylene-β-lactams and synthetic applications of α-methylene-β-lactams are also reached. In the process, it is believed that an intramolecular 1,2-addition of N-propiolamide and sequential C-C bond migrating cleavage are involved.