Thermal rearrangement of some benzoin arylsulfonylhydrazone derivatives

Abstract: Thermolysis of benzoin benzene-p-sulfonylhydrazone I in nitrogen atmosphere at 200°C leads to the formation of numerous products among which the following were identified: ammonia, benzoic acid, benzophenone, benzil, aniline, diphenyl acetylene, deoxybenzoin, N-benzylbenzamide, diphenyldisulfide, diphenylthiosulfone, S-phenylthiobenzoate, benzenesulfonamide, 2-phenylindole, 2,3,4,5-tetraphenylfuran, 2,4,5-triphenylimidazole, and 2,4,5-triphenyloxazole. Similarly, thermolysis of I in the presence of isoquinoline as a radical trap under the same conditions gave 1-phenylisoquioline in addition to the previously mentioned products. Analogous results were also obtained for thermolysis of benzoin toluene-p-sulfonylhydrazone II. The formation of such products which implies the homolysis of different bonds in the benzoin derivatives followed by reaction of the so formed radicals. [Copyright &y& Elsevier]