Synthesis of 2-Amidothiophenes via Fiesselmann-Type Annulation of Activated Ynamides

A base-promoted hydrothiolation of activated ynamides using ethyl thioglycolate as the thiol partner, followed by intramolecular cyclization, enables a regioselective synthesis of functionalized 2-amidothiophenes. The method tolerates diverse functional groups, accommodates various electron-withdrawing substituents, and applies to a broad range of internal ynamides. The reaction proceeds under mild conditions, is scalable and air-tolerant, and provides rapid access to synthetically valuable 2-amidothiophene scaffolds. This method establishes a versatile platform for the construction of diverse functionalized heterocycles.