The reactions of 3-alkyl-5a–f, 3-aryl-5g–m, 3-acylamido-5n, p, 3-benzamido-5o and 3- arylamino-5q-5-alkyl-and-5-aryl-isoxazoles with tetrasulfur tetranitride antimony pentachloride complex (S4N4· SbCl5) in toluene at 90° C to reflux temperature give 3-acyl- 6a–c, e, n–q and 3-aroyl-4-substituted-1, 2, 5-thiadiazoles 6d, f–m in 13 to 61% yields as single isomers. The same reactions of 3, 4-dimethyl-5s, 5v, 4-ethyl-3-methyl-5t-5-alkyl-and ...
