Asymmetric Synthesis Of ?-lactam By N?Heterocyclic Carbene Catalyzed [3+2] Cycloaddition Reactions

Since the separation of stable N-heterocyclic carbene,it has been used as a powerful tool for construction carbon-carbon bonds and applied to various chemical reactions.In this paper,the asymmetric formal [3+2] cyclization of enal aldehydes with 2-aminoacrylates catalyzed by chiral N-heterocyclic carbenes was studied,and the desired ?-lactam derivatives were obtained in high yields with excellent diastereo-and enantioselectivities.This dissertation consists of two chapters.In the first chapter,we introduce the history of NHCs and elaborated the two important intermediates categories generated in NHCs catalyzed organic reactions in detail,they are: 1.the acyl anion equivalents;2.the homoenolate equivalents.In the second chapter,Enantioselective [3 + 2] annulation of enals with 2?aminoacrylates catalyzed by N ? Heterocyclic carbene was investigation.The ?-Lactams are found in important naturally occurring compounds show biological activity.This [3 + 2] annulation of enals with 2-aminoacrylates to generate a diverse set of ?-lactams in good yields with excellent diastereo-and enantioselectivities.Furthermore,we also proposed the possible mechanism for this [3 + 2] cyclization.