1960 年 80 巻 9 号 p. 1206-1212
Hydrolysis of astilbin (I), neoastilbin (II), isoastilbin (III), and neoisoastilbin (IV) with 5% sulfuric acid affords one mole each of L-rhamnose and dihydroquercetin, the aglycones of (I) and (IV) being obtained as the dextrorotatory trans-type and those of (II) and (III) as levorotatory trans-type (cf. Tables I and II). Application of ethanolic sodium acetate solution to (I) affords (IV) and further application of the same reagent to (IV) gives (I). Application of the same reagent to (II) affords (III), and vice versa. This change is considered to be a phenomenon arising from inversion of the conformation of 3-OR (R=L-rhamnosyl) by enolization of the carbonyl in the aglycone. It is therefore assumed that (I) is (+)-dihydroquercetin 3-L-rhamnoside, (II) is (-)-dihydroquercetin 3-L-rhamnoside, (III) is probably (-)-epi- or -cis-dihydroquercetin 3-L-rhamnoside, and (IV) is probably (+)-epi- or -cis-dihydroquercetin 3-L-rhamnoside.