PhCH=P(MeNCH2CH2)(3)N: A novel ylide for quantitative E selectivity in theWittig reaction

PhCH=P(MeNCH2CH2)(3)N (1), a semi-stabilized ylide prepared from the commer cially available nonionic base P(MeNCH2CH2)(3)N, reacts with aldehydes to g ive alkenes in high yield with quantitative E selectivity. In contrast with other ylides, this E selectivity is maintained despite changes in the meta l ion of the ionic base used to deprotonate 1, temperature, and solvent pol arity. In conjunction with structural parameters gained from the X-ray mole cular structure of 1, the pathway to E selectivity in these reactions is ra tionalized by the Vedejs model of Wittig reaction stereochemistry.