Studies On Cascade Michael-Amidation Reactions Catalyzed By N-Heterocyclic Carbene

This thesis is composed of three parts:(1) N-Heterocyclic carbene as organocatalysts has wide application in organic synthesis and it gets rapid development in the field of cascade reactions. The research progress of the cascade reactions catalyzed by N-heterocyclic carbene is reviewed.(2) We have developed an efficient cascade Michael-amidation reaction of a-bromo-α,β-un-saturated aldehydes with enamine-containing electron-withdrawing catalyzed by N-heterocyclic carbene. A series of chiral dihydropyridinones was obtained in high yields (up to 95%) and excellent enantioselectivities (up to 98% ee). The reaction has short reaction time and good substrate applicability. It provides a new route for synthesis of dihydropyridinones.(3) We have developed a cascade Michael-amidation reaction of (Z)-2-bromo-3-phenyl-acryl-aldehyde with 4-methyl-N-(2-oxo-2-phenylethyl)benzenesulfonamide for the construction of chiral y-lactams catalyzed by N-heterocyclic carbene. y-Lactam is achieved in moderate yield and high enantioselectivity. This is the first formal [3+2] cycloaddition involving a-bromo-α,β-unsaturated aldehyde.