Chitosan functionalized by citric acid: an efficient catalyst for one-pot synthesis of 2,4-diamino-5<i>H</i>-[1]benzopyrano[2,3-<i>b</i>]pyridine-3-carbonitriles 5-(arylthio) or 5-[(arylmethyl)thio] substituted
ABSTRACT Chitosan (CS) functionalized by citric acid has been used as an efficient catalyst for the preparation of 2,4-diamino-5H-[1]benzopyrano[2,3-b]pyridine-3-carbonitriles 5-(arylthio) or 5-[(arylmethyl)thio] substituted by a multicomponent reaction of salicylaldehydes, thiols and 2 equiv. of malononitrile under reflux condition in ethanol. Use of simple and readily available starting materials
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].