sncl4 grafted on silica gel: an efficient catalyst for solvent-free synthesis of coumarins via the pechmann condensation

A facile synthesis of substituted coumarins via pechmann condensation catalyzed by sncl4 grafted on silica gel is described, which was conducted under solvent-free condition in high yields. the catalyst is noncorrosive and can be easily prepared and separated from the reaction mixture. this methodology offers some advantages with regard to yield of products, simplicity in operation and green aspects.