Copper(I)-Catalyzed Heterocyclization of α-Acyl-α-alkynyl Ketene Dithioacetals: Synthesis of 3-Cyanofurans.

A new method for the synthesis of 3-cyanofurans via Cu(I)-catalyzed heterocyclization of α-acyl-α-alkynyl ketene dithioacetals in the presence of ammonium acetate has been developed. The procedure generates the cyano moiety in situ with ammonium acetate as the nitrogen source. Based upon experimental observations, a plausible reaction mechanism is proposed.