Nano-SiO2 catalyzed three-component preparations of pyrano[2,3-d]pyrimidines, 4H-chromenes, and dihydropyrano[3,2-c]chromenes

An efficient one-pot three-component procedure has been developed for the preparation of tetrahydrobenzo[b]pyrans, dihydropyrano[3,2-c]chromenes, and pyrano[2,3-d]pyrimidines using nano-SiO2 as catalyst in H2O at 70 degrees C. This methodology has a number of advantages such as: use of reusable catalyst, easy access, short reaction times, high yields, easy work up and use of non-toxic and green solvent. (C) 2017 King Saud University. Production and hosting by Elsevier B.V.