Nuclear oxidation in flavones and related compounds - Part XVII. A synthesis of Oroxylin-A
V V Sreerama Murti T R Seshadri
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Phloroacetophenone-2 ∶ 4-dibenzyl ether is prepared; it does not undergo persulphate oxidation satisfactorily. Monobenzylation of phloroacetophenone yields the 4-benzyl ether readily; it is partially methylated to the 2-methyl-4-benzyl ether. Starting with this compound, persulphate oxidation, Allan-Robinson condensation using benzoic anhydride and sodium benzoate and methylation produce 5 ∶ 6-dimethoxy-7-benzyloxyflavone Hydrobromic acid causes besides debenzylation, demethylation in the 5-position. The final product is the 6-methyl ether of baicalein which is identical with oroxylin-A isolated from the root and stem barks ofOroxylum indicum.
V V Sreerama Murti1 T R Seshadri1