Reactions of tetrasulfur tetranitride with bromomethyl ketones. One pot synthesis of 3,5‐diaroyl‐ and 3,5‐diacyl‐1,2,4‐thiadiazoles

Reactions of tetrasulfur tetranitride (S 4 N 4 ) with aryl and alkyl bromomethyl ketones 1 in chlorobenzene at reflux temperature gave 3,5‐diaroyl‐ and 3,5‐diacyl‐1,2,4‐thiadiazoles 2 in 17‐60% yields. No 1,2,5‐thiadiazoles were detected. By heating of the two reactants at 115° without the solvent were also obtained 2 in 5‐13% yields. Hydrolysis of 2 with sodium hydroxide in a mixture of ethanol, ethyl acetate, and water (v:v, 4:2:1) at 75° to 85° afforded the heretofore inaccessible 3‐aroyl‐ and 3‐acyl‐1,2,4‐thiadiazoles 3 in 17‐79% yields.