Four natural flavonols kaemferol (1), 3-hydroxy-5, 7, 4′-trimethoxy flavone (2) 3, 5-dihydroxy-7, 4′-dimethoxy flavone (3), rhamnocitrin (4) and two novel aurones 4, 6, 4′-trihydroxydihydroaurone (5), 4-hydroxy-6, 4′-dimethoxy dihydroaurone (6) were semi synthesized by reaction steps including glycoside hydrolysis, dehydrogenation, benzyl protection, O-methylation, DMDO oxidation or Algar-Flynn-Oyamade (AFO) reaction and debenzylation. The synthetic methods of DMDO oxidation for flavones to flavonols and AFO reaction for chalcones to aurones were efficient improved in the key steps. The structures of all synthetic compounds have been confirmed by NMR, MS and IR spectra. The synthetic methods have the advantages of easy availability of starting materials, simple operation and good yields, so it has considerable practical value.

Key words: Naringin, Flavonols, Aurones, dimethyldioxirane (DMDO) oxidation, semisynthesis