Tandem Aza-Michael and Intramolecular Amidic Ring-Opening Reactions of ß-Lactams: A Facile Synthesis of 4-Oxo-4,5-dihydro-1H-pyrroles from ß-Lactam Synthons.

Tandem aza-Michael addition of 3-amino-2-azetidinones with acetylenic esters and subsequent intramolecular amidic ring opening of the initially formed azetidin-3-ylaminoprop- or -but-2-enoic ester is described. The reaction provides a facile route for the formation of functionalized 4-oxo-4,5-dihydro-1H-pyrroles in good yields. [ABSTRACT FROM AUTHOR]