Multicomponent Synthesis of Benzothiophen-2-acetic Esters by a Palladium Iodide Catalyzed S-cyclization – Alkoxycarbonylation Sequence

Abstract

A catalytic carbonylative approach to the multicomponent synthesis of benzothiophene derivatives from simple building blocks [1-(2-(methylthio)phenyl)prop-2-yn-1-ols, carbon monoxide, and an alcohol)] is presented. It is based on an S-cyclization-demethylation-alkoxycarbonylation-reduction sequence promoted by the PdI2/KI catalytic system, occurring under relatively mild conditions (40 atm, 80 °C, 15 h). Benzothiophene-2-acetic esters are obtained in moderate to good yields (35–70%) starting from variously substituted substrates in combination with different alcohols as external nucleophiles (17 examples). (Figure presented.).