Abstract
Two routes for the synthesis of the flavanone naringenin are described. In the first, 3,5-dimethoxyphenol is converted to 2-hydroxy-4,6-dimethoxyacetophenone and then by condensation with anisaldehyde to 2′-hydroxy-4,4′,6′-trimethoxychalcone. The chalcone is then cyclised with aqueous hydrochloric acid and demethylated with pyridine hydrochloride to form naringenin in 45% overall yield. The condensation of 2-hydroxy-4,6-dimethoxyacetophenone with anisaldehyde could also directly produce 4′,5,7-trimethoxyflavanone, which was then converted into naringenin in 60% overall yield. In the second route, a single step for the preparation of the chalcone is used in which 1,3,5-trimethoxybenzene is acylated with p-methoxycinnamic acid. Although the synthesis of naringenin is achieved in a lower overall yield of 29%, the process is simpler.