Anomalous Stereochemistry in the Wittig Reaction Induced by Nucleophilic Groups in the Phosphonium Ylide

Abstract

Reaction of ylides from 3–9 with benzaldehyde show that carboxylate and oxido functionalities proximate to the ylide center promote anomalously high E stereoselectivity in alkene formation. Through the use of α-deuterated ylides 12–14, an internal “trans-selective Wittig” mechanism was ruled out as a principal source of exaggerated E alkene production.