Organocatalyzed Asymmetric Conjuga-te Addition Catalysts Designed And Reactions Developed

Conjugate addition reaction is one of the most important reactions for constructing carbon-carbon bond in organic synthesis. Catalytic asymmetric conjugate addition reactions have been developed rapidly in recent years, which have become a focus in the organocatalysis field.This dissertation focuses on the organocatalyzed asymmetric conjugate addition reactions, which is composed of four chapters.In chapter1, recent research progress on organocatalyzed asymmetric conjugate addition reactions of nitroolefins, oxa-conjugate addition and1,6-congugate addition has been summarized.In chapter2, a new class of chiral primary amine-thiourea catalysts bearing multiple hydrogen bonding donors have been designed and synthesized. The newly developed organocatalysts successfully catalyzed asymmetric conjugate addition of both aromatic ketones and acetone to nitroolefins. Chiral y-nitroketones were obtained in good yields with high enantioselectivities.In chapter3, by designing and synthesizing a new class of multifunctional synthons, an organocatalyzed asymmetric oxa-Michael-Michael-cyclization cascade reaction has been developed. Various chiral polycyclic chromans with five contiguous stereocenters were obtained in good yields with high stereoselectivity.In chapter4, the first chiral Bransted acids catalyzed asymmetric1,6-congugate addition of indoles to in situ generated para-quinone methides from a-phenyl-4-hydr-oxy benzyl alcohol were accomplished. This protocol provides a new method to construct diarylmethine stereogenic centers. However, the enantioselectivity is moderate at present, and further optimization is under way.