Several benzo-[b]-pyran derivatives were prepared via microwave irradiation under solvent-free conditions in the presence of InCl3·4H2O. The advantages of this method include simple operational process, environmental benignancy, and high efficiency. Moreover, the catalyst can be recovered and reused effectively for at least six times.Key words: benzo-[b]-pyran derivatives, indium trichloride, microwave irradiation.
The condensation reaction of chalcone and 1,3-cyclohexanedione was smoothly carried out in [bmim][BF4] with catalysis by FeCl3·6H2O. A series of substituted pyrans were obtained by this reaction, in high yields under mild conditions through a simple operational procedure. In addition, the ionic liquid together with the catalyst used can be conveniently recovered and efficiently reused.