ABSTRACT Three methods have been used for synthesis of pyrazolopyranopyrimidines, 3-methyl-4-aryl-4,5-dihydro-1H-pyrano[2,3-c]pyrazol-6-ones, and 1,6-diamino-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarbonitrile derivatives via four-component reactions under solvent-free conditions. Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepiniumchloride (SB-DBU+Cl−), silica-bonded n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride (SB-DABCO+Cl−), and nano silica-bonded… Click to show full abstract
ABSTRACT Three methods have been used for synthesis of pyrazolopyranopyrimidines, 3-methyl-4-aryl-4,5-dihydro-1H-pyrano[2,3-c]pyrazol-6-ones, and 1,6-diamino-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarbonitrile derivatives via four-component reactions under solvent-free conditions. Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepiniumchloride (SB-DBU+Cl−), silica-bonded n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride (SB-DABCO+Cl−), and nano silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (NSB-DBU+Cl−) as silica-supported ionic liquids catalyzed these reactions. These green, heterogeneous catalysts are separated from the reactions by simple filtration. The catalysts were recovered for at least four times without significant loss of their catalytic activities.
               
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