REACTIONS OF MONOHALOMETHYL ARYL KETOXIMES WITH TETRASULFUR TETRANITRIDE - MUCH IMPROVED SYNTHESIS OF 3-ARYL-1,2,5-THIADIAZOLES

Reactions of chloromethyl aryl ketoximes (1, X = Cl) with tetrasulfur tetranitride in p-dioxane at reflux for 4 h afforded 3-aryl-1,2,5-thiadiazoles (2) in 37-92% yields, whereas those of bromo analogs under the same conditions gave 2 and 3-aryl-4-bromo-1,2,5-thiadiazoles (3) in 48-81% and 17-31% yields, respectively. However, the compounds (3) were not formed in the presence of pyridine. Alpha-nitrosostyrene and its ring-substituted derivatives (4) are proposed as intermediates for the formations of 2.