Exploratory chemistry of 3-aroylformamido-4-aryl-1,2,5-thiadiazoles

Abstract

Apart from the previous report, the reaction of 3-(4-nitrobenzoylformamido)-4-(4-nitrophenyl)-1,2,5-thiadiazole (2a) with m-chloroperbenzoic acid in chloroform at room temperature did not proceed, whereas at reflux temperature the same reaction gave 4-nitrobenzoic acid (5) (86%) and a minute amount of a mixture of 4-nitrobenzoylformamide (6) and 3-amino-4-(4-nitrophenyl)-1,2,5-thiadiazole (7a). On the other hand the same reaction in a mixture of ethanol and chloroform (1:4) at room temperature gave 3-ethoxycarbamoyl-4-(4-nitrophenyl)-1,2,5-thiadiazole (8a) (24%) as an isolable product. When 3-aroylformamido-4-aryl-1,2,5-thiadiazoles 2 in tetrahydrofuran were treated with various alkoxides in the corresponding alcohols at room temperature, 3-amino-4-aryl- 7, 3-alkoxycarbamoyl-4-aryl- 8, and 3-aryl-4-(aryl)(hydroxy)acetamido-1,2,5-thiadiazoles 9 were isolated. The ratios of which were dependent on the kind of bases and the solvent employed. Selected compounds 2 were allowed to react with phosphorus pentasulfide in the presence of pyridine at reflux to give 3-aryl-4-arylacetarnido-1,2,5-thiadiazoles 17 (55–64%), which were also produced by the reaction of 2 with either Lawesson's reagent or hydrogen sulfide gas in the presence of pyridine at reflux.