Two new ether-linked proanthocyanidins, epioritin-(4beta-->3)-epioritin-4beta-ol and epimesquitol-(4beta-->4)-epioritin-4beta-ol, were isolated from the heartwood of Acacia caffra. Their structures and absolute configurations were established by spectroscopic methods and syntheses.
epioritin-(4beta-->3)-epioritin-(4beta-->6)-epimesquitol-4alpha-ol, were identified in the heartwood of Acacia caffra. The ethereal interflavanyl bond is readily susceptible to reductive cleavage with sodiumcyanoborohydride in trifluoroaceticacid/dichloromethane which hence permits the unequivocal assignment of the absolute configuration of constituent flavanyl units.
首个同时具有 CC 和 COC 间黄烷键键的三黄酮类化合物,epioritin-(4beta-->6)-epioritin-(4alpha-->4)-epioritin-4beta-ol,epioritin-(4beta-->3)-epioritin-( 4beta-->6)-epioritin-4beta-ol 和epioritin-(4beta-->3)-epioritin-(4beta-->6)-epimesquitol-4alpha-ol,在相思树的心材中被发现。醚间黄烷键很容易在三氟乙酸/二氯甲烷中用氰基硼氢化钠还原裂解,因此可以明确指定组成黄烷单元的绝对构型。