Abstract
The method of Pew [J. Am. Chem. Soc., 70, 303 (1948)] for the reduction of quercetin with sodium carbonate and hydrosulfite was examined and it was found that an improvement could be effected by the addition of 2 moles of boric acid to 1 mole of quercetin in order to retain solubility of quercetin during reduction. By this improvement, betterment of the yield and purity is obtained of the reduction product, distylin (3, 3′, 4′, 5, 7-pentahydroxyflavanone), m.p. 230-232° (acetate, m.p. 154-155°), giving positive zinc-hydrochloric acid reaction. The same reaction was carried out on myricetin by which the improved method was found to give better yield and quality of the reduction product, ampeloptin (3, 3′, 4′, 5, 5′, 7-hexahydroxyflavanone), m.p. 239-241° (acetate, m.p. 170-172°), giving positive zinc-hydrochloric acid reaction.
