N-Heterocyclic Carbene Catalyzed Oxidative Annulation Of β-Bromoenal And1,3-Dicarbonyl Compounds

N-heterocyclic carbene (NHC) catalysis is the hot spot in the organic synthesis chemistry in recent years. Compared with metal catalysis, organic catalysis is characteristic of high activity, simple operation and friendly environmental. Nucleophilic oganocatalyst in umpolung reaction can transform molecule nuclear/electrophilic center, change the conventional reaction model and open a non-traditional method to construct C-C bond, it has great application value in the design of multicomponent synthetic or multi step reaction. Carbeen is the general name of methylene and its derivatives and is formed in organic reaction. Different from positive and negative carbon ion, it is another kind of active intermediates. Just as other carbeens, N-heterocyclic carbene (NHC) is electric neutral and possess a bivalent carbon atom with an electron sextet, and is a nucleophilic organocatalyst that can efficiently catalyze the umpolung reactions of electrophilic aldehydes via the "Breslow intermediate" to realize the benzoin condensation, stetter reaction and other acylation reactions. When functioned with a, β-unsaturated aldehyde, it changes the polarity of y-carbon atom to nuclear, and results in a series of reactions.This work is consisted of two chapters. In the first chapter, we introduced the structure and preparation of the N-heterocyclic carbeen; the reactions with N-heterocyclic carbeen as organocatalyst were reviewed; the application of homoenolate and a,(3-unsaturated acyl azolium in the reactions were reviewed.In the second chapter, we investigated N-heterocyclic carbeen catalyzed oxidative annulation of3-halogenated-α,β-unsaturated aldehyde with1,3-dicarbonyls, we screened reaction conditions and under the optimal condition we explored the universality of the substrates. We found that the substrate is widely applicable, and we can get product in moderate to good yields.