Synthesis and Photocyclization of 1,2,4-Triazole-3-thiones

Irradiation of thienyl and other substituted triazolothiones in a thin film reactor at 254 nm in an acetonitrile-dilute sodium hydroxide medium, furnished the respective triazolobenzothiazoles and, in some cases, the desulfurized product. The irradiation of anilinomethyl-, and aryloxymethyltriazolothiones under the above conditions also furnished the respective cyclized products and desulfurized compounds. Irradiation of benzyl substituted triazole thiones in the presence of triethylamine in benzene furnished the corresponding triazolothiazine and triazolodibenzazepine. Reaction of glycine hydrazide with aryl isothiocyanates furnished the triazolothiones, wherein glycine hydrazide functioned as a hydrazine-transferring agent. Irradiation of o-chlorophenyl substituted thione in basic acetonitrile medium furnished triazolodibenzdiazepine, whereas, the benzyl derivative furnished the triazolobenzothiazine.