Investigation On The Synthesis Of Alkenes Mediated By Phosphines And Electron-deficient Alkenes

The Wittig reaction is one of the most import reactions employing for the construction of carbon-carbon double bounds in organic synthesis. The one-pot protocol for the Wittig reaction has been widely reported in the presence of bases in most cases. There is no general method to efficiently realize the one-pot Wittig reaction ofα-halo esters,α-halo amides, andα-halo ketones. Furthermore, theα-halo carbonyl compounds bearingα-alkyl substituent have hardly been explored in the one-pot Wittig reaction. There is little report about the synthesis of alkenes by ylide and imines, especially the synthesis of alkenes by stable ylide and imines . And high temperature is needed in the reactions about the synthesis of alkenes by half stable ylide and imines. Meanwhile, the yield is not good and few substrates are explored.Zwitterions, generated by the Michael-type addition of phosphines to electron-deficient alkenes, could serve as an organic base to deprotonate phosphonium formed by the nucleophilic attack of the phosphine toα-halo carbonyl compound. The resulting phosphorus ylide could react with aldehyde to give alkene. Herein, we report a highly stereoselective one-pot Wittig reaction of aldehydes with halo carbonyl compounds for the synthesis of 1,2-disubstituted and trisubstituted alkenes.The substrates can be a-bromoacetates, a-alkyl-a-bromoesters, a-bromoacetamides, a-alkyl-a-bromoamides, a-haloketones, and a-alkyl-a-chloro ketones. The reacions condition is mild, without use of bases. The trisubstituted alkenes which selectivity is not well controlled , also have excellent selectivity. This protocol is also useful for an intramolecular Wittig reaction under high dilution conditions. By the treatment of substrate, we developed with our reactant condition, We get a 13-membered macrolide with exclusive E selectivity.Phosphorus ylide might undergo Michael addition to the electron-deficient alkene and subsequent proton transfer to generate new phosphorus ylide. The new phosphorus ylide could react with aldehyde to give trisubstituted alkenes. Thus, a phosphine-mediated one-pot, three-component reaction of aldehyde,α-halo carbonyl compound, and an electron-deficient alkene could be developed to afford trisubstituted alkenesWe report a one-pot reaction of imines with halo carbonyl compounds for the synthesis of 1,2-disubstituted and trisubstituted alkenes in the presence of phosphines and electron-deficient alkenes, using water as solvent . By surveying of the solvent and changing the type of imines, we have improved the selectivity and yield. Besides, the range of substrates is wide and the types of alkenes is many..