Microwave-and Photoirradiation-Induced Staudinger Reactions of Cyclic Imines and Ketenes Generated from a-Diazoketones.A Further Investigation into the Stereochemical Process

摘要

Reactions of ketenes generated from alpha-diazoketones with a series of acyclic and cyclic imines were investigated under both microwave and photoirradiation conditions.The results indicate that the zwitterionic azabutadiene-type intermediates yielded from imines and ketenes undergo a conrotatory ring closure exclusively to produce beta-lactams.It is notable that no Woodward-Hoffmann product was found under the ultraviolet irradiation.The photoirradiation-induced Staudinger reaction shows a different stereoselectivity from the electrocyclic reaction of substituted 1,3-butadiene.