A highly tunable stereoselective olefination of semistabilized triphenylphosphonium ylides with N-sulfonyl imines.

摘要: The Wittig reaction involving direct olefination of triphenylphosphonium ylides (Ph3P═CHR) with aldehydes is arguably the most often used method for alkene synthesis, but in general it yields mixtures Z- and E-alkenes semistabilized (R = aryl or vinyl). We have developed a simple efficient protocol to improve stereoselectivity significantly by replacing N-sulfonyl imines, which possess distinct electronic steric properties relative aldehydes. A broad range aromatic, α,β-unsaturated, aliphatic imines bearing appropriate groups smoothly undergo various benzylidenetriphenylphosphoranes allylidenetriphenylphosphoranes under mild conditions afford an array both E-isomers conjugated alkenes good excellent greater than 99:1 stereoselectivity. Moreover, this tunable has been successfully applied highly stereos...