MCRs for preparation of chromenopyridines under reflux conditions and chromenes at room temperature conditions from different salicylaldehydes, malononitrile and different thiols (mol ratio = 1:2:1) were established. Mechanistic investigation suggests that the MCRs undergo different pathways at different temperatures and catalyzed by different organic bases. The structure of chromenopyridine and chromene are confirmed by crystal X-ray crystallography. (C) 2014 Kai Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Highly efficient synthesis of benzopyranopyridines via ZrP<sub>2</sub>O<sub>7</sub>nanoparticles catalyzed multicomponent reactions of salicylaldehydes with malononitrile and thiols
ZrP2O7 nanoparticles as an efficient catalyst have been used for the preparation of benzopyrano[2,3-b]pyridines from the four-component condensation reaction of salicylalde-hydes, thiols, and 2 equiv. of malononitrile under reflux conditions in ethanol in excellent yields and short reaction times.[GRAPHICS].