Study Of Asymmetric N-H Insertions And Michael Acceptor Trapping Reactions Based On Ammonium Ylides

The enantioselective construction of N-H bond represents a highly effective route to new chiral compounds in modern organic synthesis. Especially, the enantioselective insertion of α-diazoesters into an N-H bond is a fast and efficient method to get α-amino acid derivatives. Therefore, the development of enantioselective versions of the N-H insertion through α-diazoesters reaction has attracted considerable attention. Recently, transition-metal catalyzed reaction has been an important access to carbon-heteroatom chemical bond.In this thesis, we developed a novel cooperative catalytic system of achiral dirhodium(Ⅱ) acetates, chiral sulfonamide urea and achiral sulfonic acid for asymmetric N-H insertion reactions. Prochiral ammonium ylide intermedi-ates, generated in situ from α-diazoesters and carbamates initiated by dirhodium(Ⅱ) acetate, underwent asymmetric protonation with a considerable enantioselectivity in the presence of chiral sulfonamide urea and achiral sulfonic acid as co-catalysts. The co-catalysts of chiral sulfonamide urea and achiral sulfonic acid were considered as a chiral proton shuttle assisting the asym-metric proton transfer process to control the enantioselectivity. This methodology provides an efficient and mild approach to α-amino acid derivatives in high yields with moderate enantioselectivity.The second part in this thesis, we develop a highly diastereseclective Micheal reaction of diazabenzenes with anilines and unsaturated ketones, which provides an highly efficient method to synthetize multisubstituted α-amino acid in good yield with high diastereseclectivity.