PhCH=P[MeNCH(2)CH(2)](3)N: a novel ylide for quantitative E selectivity in the Wittig reaction

PhCH=PMeNCH(2)CH(2)](3)N (1), a semi-stabilized ylide prepared from the commercially available nonionic base PMeNCH(2)CH(2)](3)N, 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.