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].