PhCHP(MeNCH₂CH₂)₃N:  A Novel Ylide for Quantitative E Selectivity in the Wittig Reaction

PhCHP(MeNCH₂CH₂)₃N (1), a semi-stabilized ylide prepared from the commercially available nonionic base P(MeNCH₂CH₂)₃N, reacts with aldehydes to give alkenes in high yield with quantitative E selectivity. In contrast with other ylides, this E selectivity is maintained despite changes in the metal ion of the ionic base used to deprotonate 1, temperature, and solvent polarity. In conjunction with structural parameters gained from the X-ray molecular structure of 1, the pathway to E selectivity in these reactions is rationalized by the Vedejs model of Wittig reaction stereochemistry.