Cascade Synthesis Of Furan, Pyran And Pyridine Derivatives Catalyzed By N-heterocyclic Carbenes

The discourse includes four sections.In the first part, the development of N-heterocyclic carbenes (NHCs) as catalysts inorganic reactions was reviewed, including Benzoin condensation, Stetter reaction, a3-d3umpolung, ring-opening and other kinds of reactions. The base of the selection of thesubject, the creative points and the research techniques were involved.In the second part, we shall report that a NHC-involved, highly efficient,multicomponent synthesis of2,3-diarylated furans under solvent-free conditions. Thenew protocol has the advantages of high yield, short reaction time, simple operation andenvironmental friendliness.In the third part, we disclosed a new cascade strategy to the synthesis offuro[3,2-c]chromen derivatives via aryl aldehyde and4-hydroxycoumarin triggered byN-heterocyclic carbene (NHCs) under solvent-free conditions. It provides a greensynthestic strategy for the synthesis of furo[3,2-c]chromen derivatives and expandsapplications of N-heterocyclic carbenes in organic synthesis.In the forth part, we studied the reaction of α,β-dibromoaldehyde and1,3-dinucleophiles under NHC catalysis which afforded a series of dihydropyranonesand dihydropyridines. The reactions were conducted under mild conditions and wereeasy to run.All of the products were characterized by their IR and1H NMR. The structures ofsome products were confirmed by13C NMR and X-ray diffraction. All of the possiblereaction mechanisms were put forward.