TFA-mediated synthesis of functionalized pyrano[2,3-c]pyrazoles from pyrazol-3-ones, active carbonyl compounds and tert-BuOH

Magnetically recoverable nanocatalyst for the synthesis of pyranopyrazoles: CoFe2O4@SiO2-HClO4

“…Subsequently, many synthetic routes for development substituted derivatives of pyrano [2,3-c]pyrazoles [12], spiro-pyrano [2,3-c]pyrazoles [13] and dihydropyrano [2,3-c]pyrazoles [14] were also reported. Recently, the most common and convenient approach to synthesize a library of various pyrano [2,3-c]pyrazoles was reported by catalyzed multicomponent reactions [15]. A catalyst is a substance that enhances the rate of reaction by lowering the activation energy.…”

Rapid synthetic approaches to libraries of diversified 1,2-dihydrochromeno[2,3-c]pyrrole-3,9-diones and 3-(2-hydroxyphenyl)-4,5-dihydropyrrolo[3,4-c]pyrazol-6(1H)-ones

“…In contrast, synthetic methodologies to access chromone-fused rings are scarce, especially those involving construction of chromone-fused heterocyclic compounds. Existing reviews summarize synthetic approaches to fused pyrazoles [14][15][16], chromone-pyrazolefused compounds [17], azachromones, azachromanones [18]. A unique pyrano [2,3-c]pyrrole bicyclic skeleton, exhibiting antioxidant activity [19][20][21][22][23] and rarely detected in nature, was found in Pyranonigrins-secondary metabolites produced by Aspergillus niger.…”