Chitosan‐Based Heterogeneous Catalysts for Enantioselective Michael Reaction

Qin, Yanyan; Zhao, Wei; Yang, Lili; Zhang, Xuan; Cui, Yuanchen

doi:10.1002/chir.22058

Cited by 39 publications

(23 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The grafting of 4-vinylpyridine onto chitosan was conducted using the same procedure reported in the literature [21], a typical heterogeneous method in which chitosan powder (1.00 g) was suspended in distilled water (50 mL) and mixed with 3 × 10 −3 M of redox initiator mixture (1:0.75) K 2 S 2 O 7 and NaHSO 3 , respectively. 4-Vinylpyridine monomer (1.05 g, 10 mmol) was added and the reaction was conducted at 55 °C for 3 h. At the end of reaction time, the graft copolymer was filtered off and washed with water and was then extensively purified with hot ethanol using the Soxhlet extraction technique to get rid of the unreacted monomer.…”

Section: Methodsmentioning

confidence: 99%

“…So far a diversity of such catalyses were employed [19,20]. Moreover, chitosan, a chiral polysaccharide, has been used as an efficient catalyst for enantioselective syntheses that result in the creation of asymmetric products with chiral center(s) [21,22,23,24,25]. Previously, while using chitosan [9,11], we suffered from some disadvantages of this catalyst namely, that it afforded low yields of products in many of the investigated reactions and it could not easily be recycled because of its high hygroscopicity, leading it to form gels.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Chitosan Based Heterogeneous Catalyses: Chitosan-Grafted-Poly(4-Vinylpyridne) as an Efficient Catalyst for Michael Additions and Alkylpyridazinyl Carbonitrile Oxidation

Khalil

Al‐Matar

2013

Molecules

View full text Add to dashboard Cite

Chitosan-grafted-poly(4-vinylpyridine) (Cs-PVP) copolymers could be synthesized under heterogeneous conditions in presence of a potassium persulfate and sodium sulfite redox system. The synthesized graft copolymer could be utilized effectively, in the form of beads, as an efficient catalyst for Michael additions of active methylenes to functionally substituted alkenes. Moreover, methyl moiety oxidation in methyl pyridazinyl carbonitriles by H2O2 in the presence of chitosan-g-polyvinyl pyridine–supported iron (III) complex, Cs-PVP/Fe, could be affected. A variety of pyrans, naphthopyrans, and thiopyrans could be synthesized efficiently in the presence of these graft copolymer beads by novel catalytic routes. These polymeric catalysts could be used instead of the old toxic commercial organic basic catalysts, piperidine or pyridine, and could be readily isolated from the reaction mixture and recycled several times without significant loss of catalytic activity.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chitosan Based Heterogeneous Catalyses: Chitosan-Grafted-Poly(4-Vinylpyridne) as an Efficient Catalyst for Michael Additions and Alkylpyridazinyl Carbonitrile Oxidation

Khalil

Al‐Matar

2013

Molecules

View full text Add to dashboard Cite

show abstract

“…[142] Two modified heterogeneous catalysts: quinine-supported chitosan (CS-QN) and cinchonine-supported chitosan (CS-CN) were prepared and compared with the homogeneous quinine (QN), cinchonine (CN), and quininesupported polystyrene (PS-QN; Scheme 20).…”

Section: Michael Additionmentioning

confidence: 99%

Chitosan as a Sustainable Organocatalyst: A Concise Overview

Kadib

2014

ChemSusChem

200

View full text Add to dashboard Cite

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.

show abstract

“…Chitosan-grafted poly(4-vinylpyridine) (CS-PVP) was then engaged in Michael additions between various nucleophiles and benzylidenemalonitrile in ethanol at reflux, leading eventually to annulated products, some of which are listed in Table 2. [39] The polysaccharide was functionalised under homogeneous conditions by nucleophilic displacement of the tosylate-activated C-9 hydroxy group by the primary amine of the glucosamine unit. It was shown that chitosan-supported pyridine was more efficient than simple chitosan in all studied cases, improving the yields between 15 and 35 %.…”

Section: Brønsted Base Catalysismentioning

confidence: 99%

Chitosan: An Upgraded Polysaccharide Waste for Organocatalysis

2015

View full text Add to dashboard Cite

Green chemistry, directed towards the sustainable adaptation of human activity, is part of our society. Catalysis and waste upgrading are central aspects of green chemistry. Bringing them together would afford efficient chemical processes from the point of view of sustainability. Chitosan is a polyglucosamine generated from chitin, an abundant polysaccharide recycled from industrial marine wastes. Organocatalysts show some advantages over metallocatalysts in that they do not involve non‐renewable rare metals. However, they have drawbacks such as the need for high loadings and difficulties of recovery. This microreview presents recent achievements in the field of organocatalytic reactions promoted by chitosan as a heterogeneous catalytic material. Various organic reactions are reported, in which chitosan is engaged either as an insoluble organocatalyst or as a support for organocatalysts, being easily recycled and reused. Influences on the reaction outcomes are discussed. Although most reactions produce achiral products, a few asymmetric ones have emerged, demonstrating the capacity of chitosan to transfer its stereochemical information.

show abstract

Chitosan‐Based Heterogeneous Catalysts for Enantioselective Michael Reaction

Cited by 39 publications

References 34 publications

Chitosan Based Heterogeneous Catalyses: Chitosan-Grafted-Poly(4-Vinylpyridne) as an Efficient Catalyst for Michael Additions and Alkylpyridazinyl Carbonitrile Oxidation

Chitosan Based Heterogeneous Catalyses: Chitosan-Grafted-Poly(4-Vinylpyridne) as an Efficient Catalyst for Michael Additions and Alkylpyridazinyl Carbonitrile Oxidation

Chitosan as a Sustainable Organocatalyst: A Concise Overview

Chitosan: An Upgraded Polysaccharide Waste for Organocatalysis

Contact Info

Product

Resources

About