A convenient synthesis of ethyl furo[2,3-<i style="">h</i>] flavone/chromone-8-carboxylates

Abstract

1671-1676The reaction of 8-formyl-7-hydroxyflavones/chromone 2a-i with diethyl bromomalonate in the presence of K2CO3/toluene and tetrabutylammoniumbromide (TBAB) as a phase transfer catalyst under nitrogen atmosphere affords ethyl furo[2,3-h]flavone-8-carboxylates 3a-h and ethyl 2-(2'-furyl)-3-methyl-furo[2,3-h]chromone-8-carboxylate 3i (Method A). The reaction of 2a-i with ethyl bromo acetate in powdered K2CO3/dioxane affords the same products 3a-i (Method B)