Ionic Liquid-Mediated Darzens Condensation: An Environmentally-Friendly Procedure for the Room-Temperature Synthesis of α,β-Epoxy Ketones

This room-temperature Darzens condensation of α-chloroacetophenone with various aromatic aldehydes mediated by [bmim][BF4] ionic liquid in the presence of sodium tert-butoxide resulted in the sole formation of good to excellent yields of trans-α,β-epoxy ketones in short time periods. In contrast, tert-butyl 2-chloroacetate underwent Darzens reactions with aldehydes giving mixtures of both cis and trans products with low selectivity. In all reactions, the ionic liquid was recovered and reused in the subsequent reactions without significant loss of activity