Sequential One-Pot Synthesis of Tri- and Tetrasubstituted Thiophenes and Fluorescent Push-Pull Thiophene Acrylates Involving (Het)aryl Dithioesters as Thiocarbonyl Precursors

Abstract

An efficient, one-pot three component synthesis of highly functionalized tri- and tetrasubstituted thiophenes has been reported involving (het)aryl dithioesters as thiocarbonyl precursors. Thus, sequential base mediated condensation of readily available (het)aryl active methylene ketones with (het)aryl dithioesters followed by S-alkylation of the resulting enethiolate salts with activated halomethylene compounds and concurrent intramolecular aldol-type condensation of S-alkylated compounds affords substituted thiophenes in excellent yields. The methodology has also been extended for the synthesis of highly fluorescent push-pull substituted thiophene-5-acrylates by using bromocrotonate as the activated methylene alkylating agent.