Synthesis of 8-chloro-3',4',5,7-tetrahydroxyisoflavone possessing antioxidant activity.

hydroxyisoflavone (1) were isolated from the cultured broth of Streptomyces sp. OH-1049 by Omura et al}'2\ Among them, 1 is a novel isoflavonoid possessing a chlorine atom in the molecule. This work is about the synthesis of 1. The starting material of the synthesis was 2-chloro-3,5-dimethoxyphenol (2) which was prepared from 3,5-dimethoxyphenol according to the method of Grove et al.3\ Acetylation of 2-chloro3,5-dimethoxyphenol (2) afforded 2-chloro-3,5dimethoxyphenyl acetate (3). Then the compound 3 was rearranged into 3-chloro-2-hydroxy-4,6-dimethoxyacetophenone (4) with A1C13 in nitrobenzene. 3'-Chloro-2'-hydroxy-3,4,4',6'-tetrameth-