A novel cyclization reaction of pyridinium 1,4-zwitterionic thiolates and propiolic acidderivatives mediated by triethylamine is described, which allows the facile synthesis of indolizines under mild reaction conditions. The net transformation involves an acetylide-driven formal [5 + 1] annulation reaction followed by a spontaneous ring-contraction/sulfur extrusion process of transient pyridothiazine
An efficient and experimentally rapid protocol for the synthesis of hitherto unreported 2,3-dicarboalkoxy-4-aroyl/heteroaroyl/alkanoyl thiophenes has been developed via 1–2 (C–S) and 3–4 (C–C) bond connections promoted by 4-dimethylaminopyridine (DMAP). Optimally, the reaction takes only 3–5 min when β-oxodithioester and dialkyl acetylenedicarboxylate are stirred in DCM at room temperature in the presence