Acid-Catalyzed Condensation of Primary/Secondary Amines with 2-Oxo-2-aryl-N-arylethanethioamides: A Highly Regioselective Synthesis of α-Oxoamidines

Abstract

In this letter, we present the synthesis of α-oxoamidines by the condensation of primary/secondary amines with N-aryl-α-oxothioamides catalyzed by benzoic acid in toluene at 80 °C. The required substrates N-aryl-α-oxothioamides were synthesized by the sodium hydride induced condensation of aromatic amines with α-oxodithioesters. The amines highly regioselectively reacted with thiocarbonyl group over carbonyl group to afford α-oxoamidines. The present method overcomes the limitations of the earlier reported methods.