p‑TSA/Base-Promoted Propargylation/Cyclization of β‑Ketothioamides for the Regioselective Synthesis of Highly Substituted (Hydro)Thiophenes

Abstract

Metal-free, p-toluenesulfonic acid (p-TSA)- mediated, straightforward propargylation of β-ketothioamides with aryl propargyl alcohol has been achieved at room temperature. In addition, the reaction also provided thiazole rings as byproducts. Furthermore, the propargylated thioamides undergo intramolecular 1,5-cyclization to afford fully substituted (hydro)thiophenes in the presence of base. Notably, the approach is pot, atom, and step economical (PASE)