Phenylselenenyl sulfate induced cyclization of allylhydrazines. Synthesis of pyrazole derivatives

Article abstract of DOI:10.1016/S0040-4020(97)00116-6

Allylhydrazines react with phenylselenenyl sulfate, produced by diphenyl diselenide and ammonium persulfate in the presence of trifluoromethanesulfonic acid, to afford phenylseleno substituted pyrazolidines. Under the reaction conditions employed, these suffer dehydrogenation and oxidative deselenenylation to eventually give pyrazole derivatives.