OXIDATION OF HYDRAZONES BY HYPERVALENT ORGANOIODINE REAGENTS - REGENERATION OF THE CARBONYL GROUP AND FACILE SYNTHESES OF ALPHA-ACETOXY ANDALPHA-ALKOXY AZO-COMPOUNDS

Various hydrazone derivatives of alpha-keto esters were prepared. The carbonyl group was readily regenerated in high yield from phenylhydraz ones through oxidative hydrolysis using hypervalent organoiodine(III) reagents-either bis(trifluoroacetoxy)-iodobenzene (BTIB) in aqueous ac etonitrile or hydroxy (tosyloxy)iodobenzene (HTIB) in chloroform, alph a-Acetoxy phenyl- or methylazo compounds were readily synthesized by o xidation of the corresponding hydrazones with iodobenzene diacetate (I BDA) in dichloromethane or acetic acid. alpha-Methoxy phenyl- or methy lazo compounds were also prepared by oxidation of the hydrazones in me thanol. The mechanisms of the oxidation reactions are discussed. Copyr ight (C) 1996 Elsevier Science Ltd