Reactions of tetrasulfur tetranitride with alkyl aryl ketoximes: synthesis of 3-aryl- and 3-alkyl-4-aryl-1,2,5-thiadiazoles

Tetrasulfur tetranitride (S4N4) was treated with various alkyl aryl ketoximes having two hydrogens at the α-carbon atom to the oxime functionality in p-dioxane at reflux to give 3-substituted and 3,4-disubstituted 1,2,5-thiadiazoles in moderate yields. Reaction with isobutyrophenone oxime under the same conditions did not give the 1,2,5-thiadiazole derivative. On the other hand, the reaction with cyclohexanone oxime in p-dioxane and toluene afforded 4,5-dihydrobenzo[1,2-c:3,4-c′]bis[1,2,5]thiadiazole in 6 and 7% yield, respectively.