Abstract
The Aglycone B (I), m.p. 231-232°, extracted from the bark of Engelhardtia formosana Hay correspond to formula C15H12O6, gives a tetraacetate (amorphous) of m.p. 50°, C15H8O6(CH3CO)4⋅H2O, pentaacetate (amorphous) of m.p. 200°, C15H7O6(CH3CO)5, monomethyl ether of m.p. 171-172°, C15H11O5(OCH3), dimethyl ether of m.p. 189-190°, C15H10O4(OCH3)2, trimethyl ether (IV) (amorphous) of m.p. 60°, C15H9O3(OCH3)3, tetramethyl ether (VII) (amorphous) of m.p. 50°, C15H8O2(OCH3)4, and tetrabenzoate (amorphous) of m.p. 130°, C15H8O6(COC6H5)4. Air oxidation of hot aqueous solution of (I) gave 3, 5, 7, 4′-tetrahydroxyflavone (kaempferol) (II), and dehydrogenation of trimethyl ether (IV) with palladium-black and cinnamic acid or application of approximately equimolar amount of alkali to the methanolic solution of (IV), yielded 3-hydroxy-5, 7, 4′-trimethoxyflavone (V). Application of alcoholic potash to the tetramethyl ether (VII) gave α-methoxychalcone (VIII). It was assumed from these experimental results that the structure of Aglycone B would be 3, 5, 7, 4′-tetrahydroxyflavanone (I″).
