A synthetic route to alpha-aminoketone derivatives via a hetero Diels-Alder reaction is described. Diacylhydrazine was oxidized by tert-butyl hypochlorite in the presence of pyridine. After evaporation, the hetero Diels-Alder reaction with diene was carried out without isolation of the azodicarbonyl compound. Quantitative hetero Diels-Alder reaction was possible with 1 equivalent of diene when Hf(OTf)(4) or AgOTf was used as the catalyst. The N-N bond of the product was cleaved by SmI2-reduction in the presence of tert-BuOH in THF. Further, ozonolysis of the C=C double bond afforded the alpha-aminoketone derivative in excellent yield.