Asymmetric Synthesis Of Spirooxindole δ-Lactones Via Oxidative N-Heterocyclic Carbene Catalysis

This thesis mainly includes the following two parts.As one of the most important organic cayalysts, N-heterocyclic carbenes (NHCs) have received increasing attention and found a broad range of application. The majority of these processes employ aldehydes as substrates, and the carbonyl carbon acting as a nucleophile by umpolung. Oxidative NHC-catalyzed reaction as one of the most investigated transformations developed rapidly, and paved a new way for organic chemistry for the speacil reactivity of azolium intermediates which formed from aldehydes upon in situ oxidation or that bearing redox active moieties. Herein we will focus on the recent development on this area.Spirocyclic oxindole architectures are present in various natural products and pharmaceuticals, and many of them have shown a wide range of biological activities. In particular, the spirooxindole 8-lactones are a potential promising class. However, very limited investigations were focused on the enantioselective synthesis of them. Based on our previous efforts on the synthesis of spirooxindoles and recent interest in NHC catalyzed asymmetric transformations, we developed an enantioselective oxidative NHC-catalyzed cascade reaction leading to the synthesis of spirooxindole δ-lactones with with excellent enantioselectivities. And we discussed the regioselectivity by employing 1-arylbutane-1,3-dione as the starting materials.