A New Synthesis of Tephrosic Acid

2′-Carboethoxymethoxy-4′,5′-dimethoxy-7-hydroxyisoflavone was prepared from 7-benzyloxy-4′,5′-dimethoxy-2′-hydroxyisoflavone via the corresponding 2′-carboethoxymethoxyisoflavone. The hydrolysis of the 7-hydroxyisoflavone with dilute alkali gave tephrosic acid (2,4-dihydroxyphenyl 2-carboxymethoxy-4,5-dimethoxybenzyl ketone) in a good yield.