A Convenient Synthesis of 2-exo-Methylene Penam, A Potent Intermediate for Newb-Lactam Antibiotics Synthesis

Tanaka, H.; Kameyama, Y.; Kosaka, A.; Yamauchi, T.; Torii, S. Tetrahedron Lett. 1991, 32, 7445.

A convenient synthesis of 2-exo-methylene penams 1 was performed by transformation of thiazoline-azetidinones, derived from penicillin G, through intramolecular Michael addition. Manipulation of the exo-methylene moiety of 1 opened new entries to 2-oxopenam and 2b-thiomethyl substituted penams, respectively.