Novel synthesis of flavonoids of Scutellaria baicalensis Georgi.

A concise and efficient total synthesis of the flavonoids baicalein, oroxylin A and wogonin was described. Intramolecular oxidative cyclization followed by demethylation of chalcone 1, readily prepared from trimethoxyphenol, afforded, depending upon the controlled conditions, baicalein or oroxylin A in excellent yields. Demethylation of 1 yielded 3, which, by oxidation with I(2)/dimethyl sulfoxide (DMSO), was readily converted to oroxylin A and wogonin after column chromatography.