Ytterbium(III) bis(perfluorooctanesulfonyl)imide catalyzed one-pot synthesis of tetrahydrobenzo[b]pyrans in fluorous biphase system

Ytterbium(III) bis(perfluorooctanesulfonyl)imide [Yb(NPf(2))(3)] has been prepared, and used as an efficient catalyst for the synthesis of 4H-benzo[b]pyran derivatives by a one-pot three-component condensation of aldehydes, active methylene compounds, and dimedone in a fluorous biphase system (FBS). The reaction proceeds smoothly and affords the corresponding 4H-benzo[b]pyrans in moderate to excellent yields. The catalyst is selectively dissolved in the fluorous phase, can be recovered simply by phase separation and reused several times without any obvious decrease of activity.