Synthesis of cis-disalicylide and of flavones containing a chromeno-[4,3-b]chromen nucleus

Abstract

Salicylic acid reacts with phosgene and slightly less than 2 mol. equiv. of triethylamine to give 1,3-benzodioxan-2,4-dione in high yield. A trace of triethylamine converts this compound into cis-disalicylide(dibenzo[b,f][1,5]dioxocin-6,12-dione) almost quantitatively. With ethyl sodioacetoacetate cis-disalicylide readily gives chromeno-[4,3-b]chromen-6,7-dione (XIII); with sodioacetylacetone it gives 6-hydroxy-6-methylchromeno[4,3-b]chromen-7-one (VIIIb).