Friedlander synthesis of novel benzopyranopyridines in the presence of chitosan as heterogeneous, efficient and biodegradable catalyst under solvent-free conditions

Siddiqui, Zeba N.; Khan, Khaliquz Zaman

doi:10.1039/c3nj00069a

Cited by 52 publications

(16 citation statements)

References 37 publications

(22 reference statements)

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“…Native chitosan is an efficient, sustainable catalyst for this reaction. [159] Optimization of the reaction rate for the condensation of 4-amino-3-formylcoumarin and indane-1,3-dione reveals that 20 mol % chitosan affords the heterocyclic product in a relatively short time. The use of Scheme 34.…”

Section: Friedländer Synthesis Of Benzopyranopyridinesmentioning

confidence: 99%

“…Condensation of 4-amino-3-formylcoumarin and indane-1,3-dione catalyzed by chitosan in different solvents. [159] aqueous or organic solvents seems to be detrimental for the catalytic activity because a longer reaction time is needed for MeOH and EtOH (5 and 8 h, respectively), and even as long as 24 h is necessary for water as a solvent (Scheme 38). By sharp contrast, solvent-free conditions enabled quantitative conversion in 2 min.…”

Section: Friedländer Synthesis Of Benzopyranopyridinesmentioning

confidence: 99%

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Chitosan as a Sustainable Organocatalyst: A Concise Overview

Kadib

2014

ChemSusChem

205

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Increased demand for more sustainable materials and chemical processes has tremendously advanced the use of polysaccharides, which are natural biopolymers, in domains such as adsorption, catalysis, and as an alternative chemical feedstock. Among these biopolymers, the use of chitosan, which is obtained by deacetylation of natural chitin, is on the increase due to the presence of amino groups on the polymer backbone that makes it a natural cationic polymer. The ability of chitosan-based materials to form open-network, macroporous, high-surface-area hydrogels with accessible basic surface sites has enabled their use not only as macrochelating ligands for active metal catalysts and as a support to disperse nanosized particles, but also as a direct organocatalyst. This review provides a concise overview of the use of native and modified chitosan, possessing different textural properties and chemical properties, as organocatalysts. Organocatalysis with chitosan is primarily focused on carbon-carbon bond-forming reactions, multicomponent heterocycle formation reactions, biodiesel production, and carbon dioxide fixation through [3+2] cycloaddition. Furthermore, the chiral, helical organization of the chitosan skeleton lends itself to use in enantioselective catalysis. Chitosan derivatives generally display reactivity similar to homogeneous bases, ionic liquids, and organic and inorganic salts. However, the introduction of cooperative acid-base interactions at active sites substantially enhances reactivity. These functional biopolymers can also be easily recovered and reused several times under solvent-free conditions. These accomplishments highlight the important role that natural biopolymers play in furthering more sustainable chemistry.

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Section: Friedländer Synthesis Of Benzopyranopyridinesmentioning

confidence: 99%

Section: Friedländer Synthesis Of Benzopyranopyridinesmentioning

confidence: 99%

Chitosan as a Sustainable Organocatalyst: A Concise Overview

Kadib

2014

ChemSusChem

205

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“…pounds of this type are usually obtained from 3-substituted coumarins, [23,[26][27][28][29] 4-substituted coumarins, [30][31][32][33][34][35] salicylic aldehydes, [36] 2-halobiarylcarboxylates, [37] or halogenated arenecarboxylates [38] by means of catalytic processes. Several authors have communicated the synthesis of 5-hydroxy-5Hbenzopyrano [4,3-b]pyridine, a reduced precursor of the pyrido [3,2-c]coumarin core structure, starting from 3-formylchromone.…”

Section: Introductionmentioning

confidence: 99%

“…Pyrido[3,2‐ c ]coumarins are important because of their photophysical and biological effects as well as their potential applications, for example, bright fluorescence, chemosensory properties, fluorescence imaging in living cells, decrease of blood sugar levels, and positive inotropic effects . Compounds of this type are usually obtained from 3‐substituted coumarins,, 4‐substituted coumarins, salicylic aldehydes, 2‐halobiarylcarboxylates, or halogenated arenecarboxylates by means of catalytic processes. Several authors have communicated the synthesis of 5‐hydroxy‐5 H ‐benzopyrano[4,3‐ b ]pyridine, a reduced precursor of the pyrido[3,2‐ c ]coumarin core structure, starting from 3‐formylchromone .…”

Section: Introductionmentioning

confidence: 99%

Domino Reactions of Chromone‐3‐carboxylic Acids with Aminoheterocycles: Synthesis of Heteroannulated Pyrido[2,3‐c]coumarins and their Optical and Biological Activity

et al. 2017

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A series of new heteroannulated pyrido[2,3‐c]coumarins have been prepared by the domino reactions of chromone‐3‐carboxylic acid derivatives with electron‐rich binucleophilic aminoheterocycles. The products contain the core structures of coumarin, pyridine, and an annulated five‐membered heterocyclic system, namely pyrazole, pyrrole, or isoazole. The fluorescence of the products was investigated. The products inhibit ecto‐5′‐nucleotidase (e5′NT) enzymatic activity.

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“…Therefore, in continuation of our interest in catalysis and in order to overcome these limitations we have grafted piperidine onto silica surface to get piperidine‐bonded silica as a novel basic heterogeneous catalyst for the synthesis of various chalcones by Claisen–Schmidt condensation under solvent‐free conditions. The catalyst was prepared through a simple protocol by condensing silica chloride with piperidine.…”

Section: Introductionmentioning

confidence: 99%

Piperidine‐functionalized silica: an efficient and environmentally benign catalyst for Claisen–Schmidt condensation

Khan

Siddiqui

2014

Applied Organom Chemis

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Piperidine‐functionalized silica as a basic heterogeneous catalyst was synthesized via a simple protocol by condensing silica chloride with piperidine. The catalyst was characterized with various techniques (FT‐IR, solid state NMR, scanning electron microscopy, energy‐dispersive X‐ray, thermogravimetric, elemental, and NH3 and CO2 temperature‐programmed desorption analyses). Surface area was also evaluated through Brunauer–Emmett–Teller analysis. Its catalytic activity was evaluated for Claisen–Schmidt condensation under solvent‐free conditions. The catalyst was easily recovered and reused up to five cycles without considerable loss of activity and was not deactivated due to amide formation. Also, this method has attractive advantages such as short reaction time, mild reaction conditions, good to excellent yield of products, easy handling of the catalyst and simple operational procedure. Copyright © 2014 John Wiley & Sons, Ltd.

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Friedlander synthesis of novel benzopyranopyridines in the presence of chitosan as heterogeneous, efficient and biodegradable catalyst under solvent-free conditions

Cited by 52 publications

References 37 publications

Chitosan as a Sustainable Organocatalyst: A Concise Overview

Chitosan as a Sustainable Organocatalyst: A Concise Overview

Domino Reactions of Chromone‐3‐carboxylic Acids with Aminoheterocycles: Synthesis of Heteroannulated Pyrido[2,3‐c]coumarins and their Optical and Biological Activity

Piperidine‐functionalized silica: an efficient and environmentally benign catalyst for Claisen–Schmidt condensation

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