Triflic acid adsorbed on silica gel as an efficient and recyclable catalyst for the addition of beta-dicarbonyl compounds to alcohols and alkenes

The silica gel supported triflic acid was readily prepared via simple absorption of TfOH onto chromatographic silica gel. This solid acid was applied as an efficient catalyst for the heterogeneous addition of various beta-dicarbonyl compounds to a series of alcohols and alkenes, which afforded moderate to excellent yields under solvent-free conditions or in nitromethane. Moreover, this silica gel supported catalyst surprisingly exhibited higher reaction yields in comparison with the homogeneous catalyst and can be readily recovered and reused up to 6 times with almost maintained reactivity and yields.