Synthesis Of Alkenes Based On Phosphines And Electron-deficient Alkenes Synthesis Of Electron-deficient Alkenes Based On C=N Double Bond Cleavge

N-sulfonyl imines are important carbon-nitrogen double bond type compounds. They are useful synthons in stereoselective organic synthesis. They can undergo many interesting reactions, such as nucleophilic addtion, cycloaddition, metallation, oxidation, elimination and so on. Comparing with aldehydes, the nitrogen of imines replace the oxygen of carbonyl group, their properties are similary in a way. For example, they both can undergo nucleophilic addtion.There are a lot of reports about nucleophilic addition of imines based on cleavge of carbon-nitrogen double bond, but up to now, the synthesis of 3-substituted 2-methylene-4-nitrobutanenitriles from N-sulfonyl imines, (cyanomethylene)triphenylphosphorane, nitromethane, and formaldehyde doesn't have been reported. The Wittig reaction is one of the most versatile synthetic methods for preparation of olefins from carbonyl compounds. And the one-pot protocol for the Wittig reaction has already been applied to the direct olefination. However, to the best of our knowledge, there is no report about one-pot reaction of N-sulfonyl imines andα-halo carbonyl compounds based on cleavge of carbon-nitrogen double bonds.In the course of exploring the synthetic utilities of carbon-nitrogen double bond cleavage of our laboratory, we found treatment of N-benzylidene-p-toluenesulfonamide with (cyanomethylene)triphenylphosphorane in nitromethane at room temperature did not at all result in the formation ofα,β-unsaturated nitrile, nitrile-stabilized phosphonium ylide was obtained instead. Then formalin was added to catch the intermediate nitrile-stabilized phosphonium ylide,after stirred many hours, and Rauhut-Currier type electron-deficient alkenes product was obitaned. Anyway we developed an unprecedented four-component reaction. In the absence of catalysts and additives, the four-component reaction proceeds smoothly at room temperature to afford target products in good to excellent yields, besides, this reaction has potentially application value to organic synthesis.In the course of exploring new reactions involoving stereoselective alkene synthesis, we found a new and efficient protocol for highly stereoselective synthesis of electron-deficient alkenes. In this experiment, we afforded corresponding electron-deficient alkenes through one pot reaction of N-sufonyl imines andα-halo carbonyl compounds mediated by phosphine and terminal alkene. By surveying of solvents and protceting groups on nitrogen of imines, we finally afforded highly stereoselective electron-deficient alkenes in environmentally bengin solvent (H2O or EtOH) using protecting group of p-nitrobenzenesulfonyl.