Alkylation of 5-(3-chlorobenzo[b]thien-2-yl)-1,2,4-triazole-3-thione with Epichlorhydrin and the Role of MW and Solid Support in the Reaction

An efficient eco-friendly approach has been adopted for the selective synthesis of 2,3- epoxypropylsulfanyltriazole 4 from the reaction of 1-chloro-2,3-epoxy-propane (2) with 5-(3- chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole-3-thione (1) under solvent free microwave conditions in the presence of a solid support. Instead, when the mixture of reactants was irradiated for prolonged time in the absence of solid support, triazolo[ 2,1-b]thiazine 3 was exclusively afforded in excellent yield. On the other hand, performing the irradiation in the presence of a base, mixtures of compounds 4 and 3 were obtained; the ratio of the two products was dependent on the nature of the base, although 4 was the major product in each case.