Oxidation of hydrazones by hypervalent organoiodine reagents: Regeneration of the carbonyl group and facile syntheses of α-acetoxy and α-alkoxy azo compounds

Article abstract of DOI:10.1016/0040-4020(96)00940-4

Various hydrazone derivatives of α-keto esters were prepared. The carbonyl group was readily regenerated in high yield from phenylhydrazones through oxidative hydrolysis using hypervalent organoiodine(III) reagents either bis(trifluoroacetoxy)-iodobenzene (BTIB) in aqueous acetonitrile or hydroxy(tosyloxy)iodobenzene (HTIB) in chloroform. α-Acotxy phenyl- or methylazo compounds were readily synthesized by oxidation of the corresponding hydrazones with iodobenzene diacetate (IBDA) in dichloromethane or acetic acid. α-Methoxy phenyl- or methylazo compounds were also prepared by oxidation of the hydrazones in methanol. The mechanisms of the oxidation reactions are discussed.