Development of a concise synthesis of the flavonoid chrysin

Abstract

Two novel routes for the synthesis of the flavonoid chrysin are described. In the first, 3,5-dimethoxyphenol (taxicatigenin) was converted to 2-hydroxy-4,6-dimethoxyacetophenone and then by condensation with benzaldehyde to 2'-hydroxy-4',6'-dimethoxychalcone. The latter was cyclised with iodine and demethylated with pyridine hydrochloride to form chrysin in 50% overall yield. In the second route, taxicatigenin was acylated with cinnamoyl chloride to form a chalcone under special conditions. This was then converted to chrysin in 42% and 56% overall yield, respectively. Several disadvantages of previous syntheses like long reaction time, tedious work-up and low overall yield have been overcome.