scholarly journals An efficient dynamic asymmetric catalytic system within a zinc-templated network

2019 ◽  
Vol 55 (55) ◽  
pp. 7970-7973 ◽  
Author(s):  
Anna Serra-Pont ◽  
Ignacio Alfonso ◽  
Jordi Solà ◽  
Ciril Jimeno
Keyword(s):  
Catalytic Activity ◽  
Complex Network ◽  
Catalytic System ◽  
Aldol Reaction ◽  
High Catalytic Activity ◽  
Asymmetric Catalytic ◽  
Direct Aldol Reaction

Enhanced cooperativity leading to high catalytic activity and stereoselectivity in the direct aldol reaction has been achieved through a complex network of simple species interacting reversibly.

One-step hydrothermal synthesis of chiral carbon dots with high asymmetric catalytic activity for enantioselective direct aldol reaction

2021 ◽  
Author(s):  
Shuang Liu ◽  
Yu He ◽  
Yu Liu ◽  
Shuaibin Wang ◽  
Yajun Jian ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Citric Acid ◽  
Hydrothermal Synthesis ◽  
Carbon Dots ◽  
Hydrothermal Reaction ◽  
Aldol Reaction ◽  
Asymmetric Catalytic ◽  
Direct Aldol Reaction ◽  
Chiral Carbon ◽  
One Step

Chiral carbon dots is prepared by a simple and one-step hydrothermal reaction at 180 °C for 2 h using citric acid and D-proline as precursors, which show high asymmetric catalytic...

Design of Novel Hydrogen-Bonding Donor Organocatalysts and Their Application to Asymmetric Direct Aldol Reaction

Synlett ◽  
2017 ◽  
Vol 28 (11) ◽  
pp. 1363-1367 ◽  
Author(s):  
Tsuyoshi Miura ◽  
Hiroshi Akutsu ◽  
Kosuke Nakashima ◽  
Hikaru Yanai ◽  
Akira Kotani ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic Activity ◽  
Aldol Reaction ◽  
Aromatic Aldehydes ◽  
Aldol Reactions ◽  
Catalytic Activities ◽  
Asymmetric Catalytic ◽  
Direct Aldol Reaction ◽  
Double Hydrogen

Asymmetric catalytic activities of various organocatalysts bearing double hydrogen-bonding donor units showing different pK a values were examined for direct aldol reactions of cyclohexanone with aromatic aldehydes. Organocatalyst with motif exhibiting the highest acidity resulted in the corresponding aldol products with the highest enantioselectivity. A good correlation has been observed between the asymmetric catalytic activity for direct aldol reactions and acidities of double hydrogen-bonding donating units.

Synthesis of 1,2-Diamine Bifunctional Catalysts for the Direct Aldol Reaction Through Probing the Remote Amide Hydrogen

2019 ◽  
Vol 6 (2) ◽  
pp. 171-176
Author(s):  
Rajasekhar Dodda ◽  
Sampak Samanta ◽  
Matthew Su ◽  
John Cong-Gui Zhao
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic Activity ◽  
Aldol Reaction ◽  
Catalytic Efficiency ◽  
Aldol Reactions ◽  
Catalyst Loading ◽  
Bifunctional Catalysts ◽  
Amide Hydrogen ◽  
Highly Efficient ◽  
Direct Aldol Reaction

Background: While proline can catalyze the asymmetric direct aldol reactions, its catalytic activity and catalyst turnover are both low. To improve the catalytic efficiency, many prolinebased organocatalysts have been developed. In this regard, prolinamide-based bifunctional catalysts have been demonstrated by us and others to be highly efficient catalysts for the direct aldol reactions. Results: Using the β-acetamido- and β-tosylamidoprolinamide catalysts, the highly enantio- and diastereoselective direct aldol reactions between enolizable ketones and aldehydes were achieved (up to >99% ee, 98:2 dr). A low catalyst loading of only 2-5 mol % of the β-tosylamidoprolinamide catalyst was needed to obtain the desired aldol products in good to high yields and high stereoselectivities. Methods: By carefully adjusting the hydrogen bonding ability of the remote β-amide hydrogen of the 1,2-diamine-based prolinamide bifunctional catalysts, the catalytic activity and the asymmetric induction of these catalysts were significantly improved for the direct aldol reaction between aldehydes and enolizable ketones. Conclusion: Some highly efficient 1,2-diamine-based bifunctional prolinamide catalysts have been developed through probing the remote β-amide hydrogen for its hydrogen bonding capability. These catalysts are easy to synthesize and high enantioselectivities may be achieved at very low catalyst loadings.

A highly reactive and magnetic recyclable catalytic system based on AuPt nanoalloys supported on ellipsoidal Fe@SiO2

2015 ◽  
Vol 3 (8) ◽  
pp. 4642-4651 ◽  
Author(s):  
Zewu Zhang ◽  
Yuming Zhou ◽  
Yiwei Zhang ◽  
Shijian Zhou ◽  
Sanming Xiang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
High Catalytic Activity ◽  
Magnetic Recyclable

A facile method based on in situ reduction is described for constructing AuPt nanoalloys on Fe@SiO2 with high catalytic activity and convenient magnetic separability.

scholarly journals Bio-assisted synthesized Ag(0) nanoparticles stabilized on hybrid of sepiolite and chitin: efficient catalytic system for xanthene synthesis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fatemeh Ghoreyshi Kahangi ◽  
Morteza Mehrdad ◽  
Majid M. Heravi ◽  
Samahe Sadjadi
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Catalytic System ◽  
Synergistic Effects ◽  
Aqueous Media ◽  
Catalytic Performance ◽  
High Catalytic Activity ◽  
Mean Diameter ◽  
High Yields

Abstract In this work, with the use of two natural compounds, chitin and sepiolite clay, a novel covalent hybrid is fabricated and applied as a support for the stabilization of silver nanoparticles with the aid of Kombucha extract as a natural reducing agent. The resultant catalytic system, Ag@Sep-N–CH, was characterized via XRD, TEM, FTIR, ICP, SEM, TGA, UV–Vis and BET. It was found that fine Ag(0) nanoparticles with mean diameter of 6.1 ± 1.8 nm were formed on the support and the specific surface area of the catalyst was 130 m2 g−1. The study of the catalytic performance of Ag@Sep-N–CH for catalyzing synthesis of xanthenes in aqueous media under mild reaction condition confirmed that Ag@Sep-N–CH exhibited high catalytic activity and could promote the reaction of various substrates to furnish the corresponding products in high yields. Moreover, the contribution of both chitin and sepiolite to the catalysis has been affirmed. It was found that hybridization of these two components led to synergistic effects and consequently improved the observed catalytic activity. Notably, the catalyst was recyclable up to several reaction runs.

scholarly journals Pd/C-Catalyzed Intramolecular C–H Arylation for the Synthesis of Phenanthridinones and Dibenzo-α-pyrones

SynOpen ◽  
2017 ◽  
Vol 01 (01) ◽  
pp. 0129-0137 ◽  
Author(s):  
Lingyu Zhao ◽  
Guodong Shen ◽  
Tongxin Zhang ◽  
Zhen Wang ◽  
Yuhua Liang
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
Industrial Applications ◽  
Metal Catalyst ◽  
High Catalytic Activity ◽  
Highly Active ◽  
Low Costs

Pd/C was found to be an efficient and convenient metal catalyst for intramolecular C–H arylation reactions in the synthesis of phenanthridinones and dibenzo-α-pyrones. A variety of phenanthridinones and dibenzo-α-pyrones were synthesized under the highly active catalytic system of Pd/C-KOAc-DMA in moderate to excellent yields. The high catalytic activity, high recyclability, low costs, and ease of removal of Pd/C, combined with its commercial availability, render this protocol attractive for both synthetic and industrial applications.

Dual functionalized task specific ionic liquid promoted in situ generation of palladium nanoparticles in water: synergic catalytic system for Suzuki–Miyaura cross coupling

RSC Advances ◽  
2015 ◽  
Vol 5 (96) ◽  
pp. 79061-79069 ◽  
Author(s):  
Jayavant D. Patil ◽  
Suyog N. Korade ◽  
Supriya A. Patil ◽  
Dipak S. Gaikwad ◽  
Dattaprasad M. Pore
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Catalytic System ◽  
Palladium Nanoparticles ◽  
Cross Coupling ◽  
Reducing Agent ◽  
High Catalytic Activity ◽  
In Situ Generation ◽  
Task Specific Ionic Liquid

A new task specific ionic liquid with hydroxyl and prolinate functionalities acts as a reducing agent and serves as a ligand and stabilizer for in situ formed palladium nanoparticles. This system displays high catalytic activity for Suzuki–Miyaura cross-coupling in water.

scholarly journals Novel Cobalt Complex as an Efficient Catalyst for Converting CO2 into Cyclic Carbonates under Mild Conditions

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 951
Author(s):  
Wei Fan ◽  
Wen-Zhen Wang ◽  
Li Wang ◽  
Xin-Gang Jia ◽  
Lei-Lei Li ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
Catalytic Mechanism ◽  
Cobalt Complex ◽  
Catalytic Performance ◽  
High Catalytic Activity ◽  
Cyclic Carbonates ◽  
Efficient Catalyst ◽  
Metal Centers ◽  
Mild Conditions

Based on the ligand H2dpPzda (1), a novel cobalt complex [Co(H2dpPzda)(NCS)2]·CH3OH(2) has been synthesized and characterized. The Complex 2 exhibited excellent catalytic performance for converting CO2 into cyclic carbonates under mild conditions. For propylene oxide (PO) and CO2 synthesis of propylene carbonate (PC), the catalytic system showed a remarkable TOF as high as 29,200 h−1. The catalytic system also showed broad substrate scope of epoxide. Additionally, the catalyst could be recycled to maintain the integrity of the structure and remained equal to the level of its catalytic activity even after seven catalytic rounds. Additionally, a possible catalytic mechanism was proposed due to the high catalytic activity which might be owing to the synergism of Lewis acidic metal centers and N group.

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