Boric Acid–Catalyzed One-Pot Access to 7-Aryl-benzopyrano[4,3-<i>b</i>] benzopyran-6,8-diones Under Aqueous Micellar Conditions

Abstract A mild protocol for the synthesis of 7-arylbenzopyrano[4,3-b]benzopyran-6,8-diones by three-component reaction of 4-hydroxycoumarin, aromatic aldehyde, and 5,5-dimethylcyclohexane-1,3-dione (dimedone) with boric acid catalyst under aqueous micellar conditions is described. Good to excellent yield, high selectivity, tolerance of several common functional and protecting groups, and green features including avoidance of organic solvent in the reaction as well as isolation stage and use of nontoxic water-compatible mild Lewis acid catalyst are key attractive features of the protocol. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

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