Advances in synthesis of monocyclic beta-lactams

Recent years have witnessed significant advancement in cycloaddition and cyclization strategies for the synthesis of monocyclic -lactams. Cycloadditions include the Staudinger's keteneimine cycloaddtions and related reaction. Cyclization reactions are reported to furnish -lactams through N1-C2, N1-C4 and C3-C4 bond formations employing substrates like -amino esters, amino alcohols, -hydroxamate esters, and -amino diazocarbonyls, etc. Some other strategies are silyl carbonylation reactions, ring-enlargement of aziridines, cleavage of one ring of a bicyclic -lactam, and functional group transformations on the -lactam rings. Recently, some multi-component reactions have also been designed. This article reviews the advances made in synthetic approaches to monocyclic -lactams during last five years.