Synthetic Studies of the Flavone Derivatives. IX. The Syntheses of Axillarin and Its Related Compounds

By using the method of Allan-Robinson’s flavone synthesis, the condensation of 3,ω-dimethoxy-2,1,6-trihydroxyacetophenone with 3,4-dibenzyloxybenzoic anhydride gave a mixture of 3,6- and 3,8-dimethoxy-3′,4′-dibenzyloxy-5,7-dihydroxyflavone (X and XI). The catalytic debenzylation of the above flavones then gave axillarin (I) and 3,8-dimethoxy-5,7,3′,4′-tetra-hydroxyflavone (IV) respectively. Axillarin 7-O-methyl ether(III) was prepared by the partial methylation of X, followed by catalytic debenzylation.