Polyvinylpolypyrrolidone-supported boron trifluoride: a mild and efficient catalyst for the synthesis of 1,8-dioxooctahydroxanthenes and 1,8-dioxodecahydroacridines

Polyvinylpolypyrrolidone-supported boron trifluoride has been studied for the synthesis of 1,8-dioxooctahydroxanthenes and 1,8-dioxodecahydroacridines. The reaction proceeded via condensation of: (1) aromatic aldehydes (1 eq.) and 5,5-dimethyl-1,3-cyclohexanedione (2 eq.) in acetonitrile at room temperature, (2) aromatic aldehydes (1 eq.), 5,5-dimethyl-1,3-cyclohexanedione (2 eq.), and aromatic amines (1 eq.) in acetonitrile at 80 A degrees C in the presence of polyvinylpolypyrrolidone-supported boron trifluoride. This procedure cleanly converted a variety of aryl aldehydes with different substituent groups at ortho, meta, or para positions to the corresponding products. Convenience and efficiency, an easy work-up procedure, high yield, and simple preparation of the catalyst are some advantages of this method. In addition, the polyvinylpolypyrrolidone-supported boron trifluoride complex is a high loaded Lewis acid, which is stable, easy to handle, and retains effective activity after several months of storage.