A Convenient Synthesis of Some Highly Functionalized Chromones and Indenones

Abstract

The condensation of hydroquinones and maleic anhydrides in an AlCl₃-NaCl melt at about 200°C is a well documented process¹ providing easy access to a number of naphthazarins; the 2,3-dihalogenated derivatives in particular are obtained in good yields². p-Chlorophenols react similarly but produce 8-chlorojuglones^3,4 very inefficiently, while other phenols give only the rearranged indanones⁴ which have been shown to arise through the intermediate chromanones⁵.