Oxidation of Hydrazines with Benzeneseleninic Acid and Anhydride

Article abstract of DOI:10.1021/jo00321a008

Benzeneseleninic acid (1) and anhydride (2) oxidize hydrazine or 1,2-disubstituted derivatives to corresponding diazenes.Hydrazides afford selenoesters 4, N,N'-diacyl- or diaroylhydrazines 5, and carboxylic acids.Benzeneselenenic acid (7) is a required intermediate in selenoester formation and may be generated independently by the reaction of triphenylphosphine with 1.Selenoesters are efficiently prepared by the slow addition of a mixture of the hydrazide and triphenylphosphine to 1 in dichloromethane solution.Polar solvents are unsuitable.Inverse addition provides compounds 5 as major products.Oxidation of hydrazides of structure HO-(CH2)nCONHNH2 gives the corresponding selenoesters 14 and acids 16 when n=11 or 14 lactones 17 and 18 when n=4 or 3.Arylhydrazines react with 1 or 2 to furnish arenes 23 and aryl phenyl selenides 24.