A facile and one-pot synthesis of new tetrahydrobenzo[b]pyrans in water under microwave irradiation

Eleven new tetrahydrobenzo[b]pyran derivatives were synthesized via a three component reaction of different aromatic aldehydes, methyl cyanoacetate and 1,3-cyclohexadione, with water as solvent under catalyst-free microwave irradiation. The structures of all the new molecules were well analysed and their structures established by using various spectral techniques (H-1 NMR, C-13 NMR, N-15 NMR and HRMS). Various advantages of reported protocol are the ease of preparation, short reaction times (10 min), aqueous solvent and excellent yields (89-98%). Additionally, this method provides a clean access to the desired products by simple workup.