Abstract
In this research, a number of new and known chromenopyrano[2,3-b]pyridine derivatives have been prepared. Initially, according to the reported procedure, pyrano[2,3-c]chromene derivatives were synthesized by the reaction between 4-hydroxycoumarin, aromatic aldehydes and malononitrile using silica sodium carbonate (SSC) as the catalyst. Next, the prepared pyrano[2,3-c]chromenes were reacted by dimethyl acetylenedicarboxylate (DMAD) or cyclohexanone in the presence of sodium carbonate to produce chromenopyrano[2,3-b]pyridine derivatives. The presented protocol avoids the use of expensive catalysts and gives useful potentially bioactive heterocycles in excellent to high yields.
Highlights
Heterocycles as the most prevalent organic compounds are present in various drugs, natural products, vitamins and bioactive compounds.[1,2,3] They have been found to be useful as anti-HIV,[4] anti-tumor,[5,6] anti-inflammatory,[7,8,9] anti-malarial,[10,11] anti-depressant, anti-microbial, anti-bacterial and anti-fungal agents.[12]
In order to optimize the conditions, the reaction between pyranochromene 4a and dimethyl acetylenedicarboxylate (DMAD) was selected as a model system
We propose a mechanism for the Na2CO3-catalyzed synthesis of chromenopyrano[2,3-b]pyridine derivatives 7 (Scheme 3)
Summary
Heterocycles as the most prevalent organic compounds are present in various drugs, natural products, vitamins and bioactive compounds.[1,2,3] They have been found to be useful as anti-HIV,[4] anti-tumor,[5,6] anti-inflammatory,[7,8,9] anti-malarial,[10,11] anti-depressant, anti-microbial, anti-bacterial and anti-fungal agents.[12]. Pyranopyridines have been proven to be the most active anti-tumor heterocyclic systems with activity against various filamentous tumors and specific activity against lung and ovarian cancer cells and antimicrobial action.[20,21] pyrazolo-[3,4-b]pyridine derivatives are an important class of fused pyridines with a broad spectrum of biological activities that find widespread use in the pharmaceutical industries.[22] Another class of fused pyridine derivatives is thiazolo[4,5-b]pyridin, which have anti-inflammatory and antimicrobial activity against human and veterinary pathogens Some of these compounds have antifungal and anti-tumor activity.[23,24]
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