Rhodium-Catalyzed C═N Bond Formation through a Rebound Hydrolysis Mechanism and Application in β-Lactam Synthesis

A rhodium-catalyzed reaction of N-hydroxyanilines with diazo compounds to produce α-imino esters was developed. Distinct from the commonly accepted 1,2-H transfer for normal X-H insertion reactions, density functional theory calculations indicate that this transformation proceeds via a novel rebound hydrolysis mechanism. Furthermore, a three-component reaction was explored to synthesize highly functionalized β-lactams in good yields and diastereoselectivities.