Role of the Through-Space 2p-3d Overlap Effect in the Wittig Reaction

Article abstract of DOI:10.1021/jo00155a010

Reactions of the ylide derived from triphenyl(3-phthalimidopropyl)phosphonium bromide with aromatic aldehydes have been reported to give exclusively the Z alkenes.On the basis of the Bestmann mechanism for the Wittig reaction, and also because of the fact that a 2,6-dimethoxyphenyl group enters into a strong through-space 2p-3d overlap interaction with an adjacent phosphonio group, we postulated that the reactions of the ylide derived from (2,6-dimethoxyphenyl)diphenyl(3-phthalimidopropyl)phosphonium bromide with aromatic aldehydes would give substantial ratios of E:Z alkenes.This proved to be the case.