Divergent Approach to the Synthesis of 2-Aryl-5-(thiophen-2-yl)-1,3,4-Oxadiazoles and -1,3,4-Thiadiazoles

The reaction of 2-(chloromethyl)-1,3,4-thiadiazoles and -1,3,4-oxadiazoles with thioacetic acid in the presence of DIPEA led to the formation of S-[(1,3,4-thiadiazol-2-yl)methyl]- and [(1,3,4-oxadiazol-2-yl)methyl]ethanethioate. A series of 2-thienyl-substituted 1,3,4-oxadiazoles and 1,3,4-thiadiazoles were obtained by the reaction of 3-chloroacrylaldehydes with (1,3,4-thiadiazol-2-yl)- and (1,3,4-oxadiazol-2-yl)methanethiols formed in situ from S-[(1,3,4-thia(oxa)diazol-2-yl)methyl]ethanethioate in methanol in the presence of K2CO3. The photophysical properties of the synthesized compounds were studied.