Acetoformic anhydride in the synthesis of chromones. 1. Synthesis of 3-hetarylchromones

It was shown that the reaction of -(het)aryl-2,4-dihydroxy- and 2,4,6-trihydroxyacetophenones with acetoformic anhydride catalyzed by sodium formate is an effective method for the preparation of chromones containing a heteroaromatic residue at the 3-position. The yield of the chromone and the rate of the reaction increase with increase in the -deficiency of this residue or in the presence of a hydroxy group in the 6-position of the starting acetophenone. In the last case the method is also applicable to the preparation of the difficulty available 3-aryl-5,7-dihydroxychromones. Chromones with a nitrogencontaining residue are formed without the use of any catalyst.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 625–631, May, 1991.