Synthesis of dihydrochromeno[4,3-b]pyrazolo[4,3-e]pyridin-6(7H)-ones involving one-pot three-component tandem Knoevenagel–Michael reaction catalyzed by n-tetrabutylammonium tribromide (TBATB)
2014; Elsevier BV; Volume: 55; Issue: 12 Linguagem: Inglês
10.1016/j.tetlet.2014.02.014
ISSN1873-3581
Autores Tópico(s)Synthesis and biological activity
ResumoThe synthesis of dihydrochromeno[4,3-b]pyrazolo[4,3-e]pyridin-6(7H)-ones was achieved through one-pot three-component reaction from 4-hydroxycoumarin, aldehydes, and 3-amino-5-methyl-pyrazole in acetonitrile using 5 mol % TBATB as the catalyst under reflux condition. The product formation is through tandem Knoevenagel–Michael reaction followed by concomitant cyclization. Simple reaction procedure, shorter reaction time, good yields, avoidance of aqueous work-up, and column chromatographic separation are some of the salient features of the present protocol.
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