A Facile Synthesis of Isopongaflavone, Atalantoflavone Dimethylether, Racemoflavone Dimethylether and their Analogues

Flavones possessing prenyl substituents occur quite frequently in nature, so do those with 2 ,2 -dimethylpyran ring system [1,2]. Many of such py­ ranoflavones exhibit interesting biological activi­ ties. A health food, designed to prevent diseases, consisted of extracts of M orbus bombycis or relat­ ed plants (containing morusin (1 ) and/or its hy­ drate) [3]. Isopongaflavone (2) otherwise known as candidin [4] was very much active against Maruca testualis and Eldana saccharirta and hence was effective as an antifeedant [5]. A talantofla­ vone dimethylether (3) displayed significant insec­ ticidal activity [6].