Ultrasound-assisted one-pot synthesis of substituted coumarins catalyzed by poly(4-vinylpyridinium) hydrogen sulfate as an efficient and reusable solid acid catalyst

Poly(4-vinylpyridinium) hydrogen sulfate solid acid was found to be efficient catalyst for synthesis of substituted coumarins via Pechmann reaction using ultrasound irradiation at room temperature and neat condition in high yields with short reaction times. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused and recovered for several times.

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► Introducing an efficient new method one-pot synthesis of substituted coumarins.
► Application of ultrasonic irradiation as the source of energy.
► Using of the halogen-free solid acid catalyst.
► Generality of the method, high yields and very short reaction times.
► Application of solvent-free condition in the reaction.