New Reaction Mode of the Horner-Wadsworth-Emmons Reaction for the Preparation of α-Fluoro-α,β-unsaturated Esters

Abstract

Excellent E-selectivity was observed in the Horner-Wadsworth-Emmons (HWE) reactions of ethyl 2-fluoro-2-diethylphosphonoacetate 1 with alkyl aryl ketones 2a-f using Sn(OSO2CF3)2 and N-ethylpiperidine. Mg(II)-promoted HWE reactions of 1 with aldehydes 2h,i afforded α-fluoro-α,β-unsaturated esters 3h,i in a Z-selective manner depending on the reaction temperatures.