A new microwave-assisted thionation-heterocyclization process leading to benzo[c]thiophene-1(3H)-thione and 1H-isothiochromene-1-thione derivatives

摘要

The first example of a tandem thionation/ S -cyclization process leading to benzo[ c ]thiophene-1(3 H )-thione and 1 H -isothiochromene-1-thione derivatives, starting from 2-alkynylbenzoic acids, is reported. The reaction is carried out in CH _(2) Cl _(2) using 1 equiv. of Lawesson's reagent under MW irradiation at 100 °C and 300 W for 1 h. Depending on the nature of the substituent at the distal β carbon of the triple bond, either benzothiophenethiones or isothiochromenethiones were obtained selectively, in high to excellent yields. The structure of the representative compounds has been confirmed by X-ray diffraction analysis.