Solvent-free synthesis of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives under microwave irradiation

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.