Abstract
The condensation of 3'-iodo-5-benzoyloxy-4', 7-dimethoxyflavone and 5-benzoyloxy-8-iodo-4', 7-dibenzyloxyflavone was carried out at 225∼230°for 40 minutes, with activated copper powder. The chloroform extract of the reaction mixture was heated with 10% H2SO4 in AcOH at 110° for 10 minutes to hydrolyze benzoyl and benzyl groups. The hydrolysate was dissolved in a mixture of dioxane and ether, and shaken with 10% K2CO3 solution to obtain yellow, sandy crystalline precipitate of potassium salt of ginkgetin. This salt was purified by recrystallization from 10% K2CO3 solution, decomposed with dilute H2SO4, and the free ginkgetin obtained was recrystallized from methyl ethyl ketone to pale yellow, small plates, m.p. 336°. Its acetate formed colorless needles, m.p. 259°. Ginkgetin and its acetate synthesized above were respectively identified with the corresponding materials of natural origin.
