Modular synthesis of conjugated enamidines and cascade annulation toward benzofuran-3-oxoacetate

A three-component reaction of aryne, DMF and isonitrile for the synthesis of the otherwise inaccessible chemotype, conjugated enamidines, is developed. Incubation with a Brønsted acid causes a cascade skeleton rearrangement of the enamidines to benzofuran-3-oxoacetates.