One-Pot Synthesis of 2-(Het)aryl/alkyl-3-cyanobenzofurans from 2-(2-Bromoaryl)-3-(het)aryl-3-(methylthio)acrylonitriles and Benzyl Carbamate.

A one-pot synthesis of 2-(het)aryl/alkyl-3-cyanobenzofurans has been reported. The overall sequence involves base-induced reaction of 2-(2-bromoaryl)-3-(het)aryl-3-(methylthio)acrylonitriles with benzyl carbamate, generating α-(het)aroyl-α-(2-bromoaryl)acetonitriles, which are in situ subjected to copper-catalyzed intramolecular O-arylation, furnishing the 2-(het)aryl/alkyl-3-cyanobenzofurans in high yields. A probable mechanism for the base-induced cleavage of 2-(2-bromoaryl)-3-(het)aryl-3-(methylthio)acrylonitriles to α-(het)aroyl-α-(2-bromoaryl)acetonitriles in the presence of benzyl carbamate has been proposed.