Chalkones: a new synthesis of chrysin, apigenin, and luteolin

Abstract

Kostanecki's first method for the synthesis of flavones involving treatment of o- acetoxychalkone dibromides with alcohiloc alkali has, hitherto, not been applicable for the synthesis of the numerous natural flavones containing a phloroglucinol nucleus, since the corresponding chalkone dibromides give benzylidenecoumaranones only, on treatment with alcoholic alkali. The observation that o- hydroxychalkone dibromides in general give flavones when they are heated above the m. p. or are treated with alcoholic potassium cynide has enabled the synthesis of chrysin, apigen, and luteolin to be effected from the corresponding chalkone dibromides.