Aza-Knoevenagel-type condensation of secondary amides: direct access to N-monosubstituted β,β-difunctionalized enamines

Abstract

An efficient approach to N-monosubstituted β,β-difunctionalized enamines, a class of versatile building blocks for the synthesis of bioactive compounds, is reported. The method is based on the triflic anhydride-mediated direct aza-Knoevenagel-type condensation of secondary amides with active methylene compounds. The reaction showed good chemoselectivity and functional group tolerance. A number of title compounds have been synthesized in good to excellent yields in one pot from readily available starting materials.