Catalytic Performance of Silica Supported Cinchona Alkaloids as Heterogeneous Catalysts for Asymmetric Michael Reaction

: Michael reaction is the nucleophilic addition of active methylene compounds to conjugated olefins, resultantly affording a variety of biologically active scaffolds with high enantiopurity. To improve the reaction yield, as well as enantioselectivity of the product, a variety of catalysts (amine-based catalysts, bifunctional L-proline amides, bifunctional squaramides, chiral ionic liquids, cinchona alkaloids, enzymes, indolinols, metal catalysts, peptide derived catalytic system, phase transfer catalysts, pyrrolidine based organocatalysts) have been investigated by a different era of chemists. Besides this, different methodologies have been developed to improve reaction yield and enantioselectivity of the targeted products with low catalyst loading. : This review article provides a concise overview of the catalysts applied recently by different scientists in the Michael addition reaction. Moreover, current strategies and potential applications of this reaction have also been illustrated in this review.

Download Full-text

ADMET Polymerization of Dimeric Cinchona Squaramides for the Preparation of a Highly Enantioselective Polymeric Organocatalyst

Catalysts ◽

10.3390/catal10050591 ◽

2020 ◽

Vol 10 (5) ◽

pp. 591

Author(s):

Mohammad Shahid Ullah ◽

Sadia Afrin Chhanda ◽

Shinichi Itsuno

Keyword(s):

Second Generation ◽

Michael Reaction ◽

Cinchona Alkaloids ◽

Cinchona Alkaloid ◽

Acyclic Diene Metathesis ◽

Chiral Polymers ◽

Admet Polymerization ◽

Reaction Condition ◽

High Yields ◽

Asymmetric Michael Reaction

Under the acyclic diene metathesis (ADMET) reaction condition, the C3-vinyl groups of cinchona alkaloids readily react with each other to form a C-C bond. A novel type of cinchona alkaloid polymers was synthesized from dimeric cinchona squaramides using the Hoveyda-Grubbs’ second-generation catalysts (HG2) by means of ADMET reaction. The chiral polymers, containing cinchona squaramide moieties in their main chains, were subsequently employed as catalysts for the enantioselective Michael reaction to give the corresponding chiral adducts in high yields with excellent enantioselectivity and diastereoselectivity. Both enantiomers from the asymmetric Michael reaction were distinctively prepared while using the polymeric catalysts, possessing pseudoenantiomeric structures. The catalysts were readily recovered from the reaction mixture and recycled several times due to the insolubility of the cinchona-based squaramide polymers.

Download Full-text

An Enantioselective Synthesis of Natural (-)-Huperzine A via Cinchona Alkaloids-promoted Asymmetric Michael Reaction

Heterocycles ◽

10.3987/com-96-s4 ◽

1997 ◽

Vol 46 (1) ◽

pp. 27 ◽

Cited By ~ 21

Author(s):

Shiro Terashima ◽

Satoru Kaneko ◽

Toshiharu Yoshino ◽

Tadashi Katoh

Keyword(s):

Michael Reaction ◽

Cinchona Alkaloids ◽

Enantioselective Synthesis ◽

Huperzine A ◽

Asymmetric Michael Reaction

Download Full-text

ChemInform Abstract: New Polymer-Supported Catalysts Derived from Cinchona Alkaloids: Their Use in the Asymmetric Michael Reaction.

ChemInform ◽

10.1002/chin.199948111 ◽

2010 ◽

Vol 30 (48) ◽

pp. no-no

Author(s):

Rosana Alvarez ◽

Marie-Agnes Hourdin ◽

Christian Cave ◽

Jean d'Angelo ◽

Pierre Chaminade

Keyword(s):

Michael Reaction ◽

Supported Catalysts ◽

Cinchona Alkaloids ◽

Polymer Supported ◽

Asymmetric Michael Reaction

Download Full-text

Ambient base-free glycerol oxidation over bimetallic PdFe/SiO2 by in situ generated active oxygen species

Research on Chemical Intermediates ◽

10.1007/s11164-020-04333-2 ◽

2021 ◽

Author(s):

Ricci Underhill ◽

Mark Douthwaite ◽

Richard J. Lewis ◽

Peter J. Miedziak ◽

Robert D. Armstrong ◽

...

Keyword(s):

Heterogeneous Catalysts ◽

Bimetallic Catalyst ◽

Electron Paramagnetic Resonance Spectroscopy ◽

Active Oxygen Species ◽

Catalytic Performance ◽

Resonance Spectroscopy ◽

Oxygen Species ◽

Paramagnetic Resonance ◽

Temperature Oxidation

AbstractLow temperature oxidation of alcohols over heterogeneous catalysts is exceptionally challenging, particularly under neutral conditions. Herein, we report on an efficient, base-free method to oxidise glycerol over a 0.5%Pd-0.5%Fe/SiO2 catalyst at ambient temperature in the presence of gaseous H2 and O2. The exceptional catalytic performance was attributed to the in situ formation of highly reactive surface-bound oxygenated species, which promote the dehydrogenation on the alcohol. The PdFe bimetallic catalyst was determined to be significantly more active than corresponding monometallic analogues, highlighting the important role both metals have in this oxidative transformation. Fe leaching was confirmed to occur over the course of the reaction but sequestering experiments, involving the addition of bare carbon to the reactions, confirmed that the reaction was predominantly heterogeneous in nature. Investigations with electron paramagnetic resonance spectroscopy suggested that the reactivity in the early stages was mediated by surface-bound reactive oxygen species; no homogeneous radical species were observed in solution. This theory was further evidenced by a direct H2O2 synthesis study, which confirmed that the presence of Fe in the bimetallic catalyst neither improved the synthesis of H2O2 nor promoted its decomposition over the PdFe/SiO2 catalyst.

Download Full-text

Exploiting the Potential of Biosilica from Rice Husk as Porous Support for Catalytically Active Iron Oxide Nanoparticles

Nanomaterials ◽

10.3390/nano11051259 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1259

Author(s):

Ana Franco ◽

Rafael Luque ◽

Carolina Carrillo-Carrión

Keyword(s):

Iron Oxide ◽

Iron Oxide Nanoparticles ◽

Rice Husk ◽

Heterogeneous Catalysts ◽

Catalytic Performance ◽

Added Value ◽

Oxide Nanoparticles ◽

Porous Support ◽

Green Materials ◽

Catalytically Active

Biomass-derived materials are put forward as eco-friendly alternatives to design heterogeneous catalysts. To contribute in this field, we explored the potential of mesoporous biogenic silica (RH-Silica) obtained from lignocellulosic waste, in particular from rice husk, as an inorganic support to prepare heterogenized iron oxide-based catalysts. Mechanochemistry, considered as a green and sustainable technique, was employed to synthetize iron oxide nanoparticles in pure hematite phase onto the biosilica (α-Fe2O3/RH-Silica), making this material a good candidate to perform catalyzed organic reactions. The obtained material was characterized by different techniques, and its catalytic activity was tested in the selective oxidation of styrene under microwave irradiation. α-Fe2O3/RH-Silica displayed a good catalytic performance, achieving a conversion of 45% under optimized conditions, and more importantly, with a total selectivity to benzaldehyde. Furthermore, a good reusability was achieved without decreasing its activity after multiple catalytic cycles. This work represents a good example of using sustainable approaches and green materials as alternatives to conventional methods in the production of high-added value products.

Download Full-text