Royal Society of Chemistry, RSC Advances, 25(6), p. 20777-20780
DOI: 10.1039/c6ra01329e
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The first example of a tandem thionation/S-cyclization process leading to benzo[c]thiophene-1(3H)-thione and 1H-isothiochromene-1-thione derivatives, starting from 2-alkynylbenzoic acids, is reported. The reaction is carried out in CH2Cl2 using 1 equiv of the 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 carbon of the triple bond, either benzothiophenethiones or isothiochromenethiones were obtained selectively, in high to excellent yields. The structure of representative compiounds have been confirmed by X-ray diffraction analysis.