<i>Z</i>-Selective Horner−Wadsworth−Emmons Reaction of α-Substituted Ethyl (Diarylphosphono)acetates with Aldehydes¹

Abstract

New Horner−Wadsworth−Emmons reagents, ethyl 2-(diarylphosphono)propionates (2), ethyl 2-(diarylphosphono)hexanoates (3), and ethyl 2-(diarylphosphono)-3-methylbutanoates (4) were prepared by alkylation of ethyl (diarylphosphono)acetates. The reaction of 2−4 with various types of aldehydes gave Z-α,β-dialkyl-α,β-unsaturated esters highly selectively. Remarkable temperature-dependent selectivity was observed in the reaction of (PhO)2P(O)CHBuCO2Et with octyl aldehyde.