Components of Root Bark ofCudrania tricuspidata; 3.1,2. Isolation and Structure Studies on the Flavonoids

A new isoprene substituted flavanone ( 1), named cudraflavanone A, was isolated from the root bark of CUDRANIA TRICUSPIDATA (Carr.) Bur. together with three known flavonoids, cycloartocarpesin ( 2), populnin ( 3), and quercimeritrin ( 4). The structure of 1 was determined on the basis of the spectral evidence and the total synthesis. The structure of euchrestaflavanone C ( 5) which had been isolated from EUCHRESTA JAPONICA Hook, f. ex Regel was also determined on the basis of the total synthesis.