New Benzyl(β‐oxido)phosphorus and ‐arsenic Ylides: Reactivity and Stereoselectivity in the Wittig Reaction

Abstract

Writing reactions with semistabilized ylides are generally stereo-unselective. Carefully taking into account previous data, the benzyl-ylides 1a and 1b were prepared and allowed to react with aldehydes. Upon reaction with piperonal and hexanal the arsenic ylide 1b afforded in each case 100% of the (E)-olefin (GC analysis).