scholarly journals Concerted Catalysis by Nanocellulose and Proline in Organocatalytic Michael Additions

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1231 ◽  
Author(s):  
Naliharifetra Ranaivoarimanana ◽  
Kyohei Kanomata ◽  
Takuya Kitaoka
Keyword(s):  
Catalytic Activity ◽  
Organic Synthesis ◽  
Michael Addition ◽  
Cellulose Nanofibers ◽  
Next Generation ◽  
Michael Additions ◽  
Asymmetric Michael Addition ◽  
First Time

Cellulose nanofibers (CNFs) have recently attracted much attention as catalysts in various reactions. Organocatalysts have emerged as sustainable alternatives to metal-based catalysts in green organic synthesis, with concerted systems containing CNFs that are expected to provide next-generation catalysis. Herein, for the first time, we report that a representative organocatalyst comprising an unexpected combination of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-oxidized CNFs and proline shows significantly enhanced catalytic activity in an asymmetric Michael addition.

scholarly journals New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions

2014 ◽  
Vol 10 ◽  
pp. 224-236 ◽  
Author(s):  
Helge Klare ◽  
Jörg M Neudörfl ◽  
Bernd Goldfuss
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic Activity ◽  
High Activity ◽  
Michael Addition ◽  
Bond Activation ◽  
High Catalytic Activity ◽  
Open Chain ◽  
High Hydrogen ◽  
Michael Additions ◽  
Asymmetric Michael Addition

Ten novel hydrogen-bonding catalysts based on open-chain PV-amides of BINOL and chinchona alkaloids as well as three catalysts based on rigid cis-PV-cyclodiphosphazane amides of N 1,N 1-dimethylcyclohexane-1,2-diamine have been developed. Employed in the asymmetric Michael addition of 2-hydroxynaphthoquinone to β-nitrostyrene, the open-chain 9-epi-aminochinchona-based phosphorus amides show a high catalytic activity with almost quantitative yields of up to 98% and enantiomeric excesses of up to 51%. The cyclodiphosphazane catalysts show the same high activity and give improved enantiomeric excesses of up to 75%, thus representing the first successful application of a cyclodiphosphazane in enantioselective organocatalysis. DFT computations reveal high hydrogen-bonding strengths of cyclodiphosphazane PV-amides compared to urea-based catalysts. Experimental results and computations on the enantiodetermining step with cis-cyclodiphosphazane 14a suggest a strong bidentate H-bond activation of the nitrostyrene substrate by the catalyst.

scholarly journals Organocatalytic Asymmetric Michael Addition of Ketones to α, β-Unsaturated Nitro Compounds

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 618 ◽  
Author(s):  
Jae Ho Shim ◽  
Si Hun Nam ◽  
Byeong-Seon Kim ◽  
Deok-Chan Ha
Keyword(s):  
Michael Addition ◽  
Chemical Yield ◽  
Nitro Compounds ◽  
Neutral Condition ◽  
High Chemical ◽  
Aromatic Ketones ◽  
Michael Additions ◽  
Asymmetric Michael Addition ◽  
Neutral Conditions ◽  
Organic Catalyst

An organic catalyst “(R, R)-1,2-diphenylethylenediamine(DPEN) derivative’’ was devel-oped as a chiral bifunctional organocatalyst and applied for asymmetric Michael additions of aromatic ketones to trans-β-nitroalkene compounds under neutral conditions. The isopropyl-subs-tituted thiourea catalyst in neutral condition provides high chemical yield and enantioselectivities (ee) (up to 96% yield, 98% ee).

Direct organocatalytic asymmetric Michael reaction of fluorine hemiaminal-type nucleophile to 4-nitro-5-styrylisoxazoles

2020 ◽  
Vol 7 (11) ◽  
pp. 1343-1348
Author(s):  
Luyao Li ◽  
Bo Zhu ◽  
Huihui Fan ◽  
Zhiyong Jiang ◽  
Junbiao Chang
Keyword(s):  
Michael Addition ◽  
Michael Reaction ◽  
Addition Reaction ◽  
Michael Addition Reaction ◽  
Asymmetric Michael Addition ◽  
Asymmetric Michael Reaction ◽  
First Time

Herein, we report a chiral bifunctional thiourea catalyzed asymmetric Michael addition reaction between 2-(trifluoromethyl)oxazol-5(2H)-one as a direct C-2-position nucleophile to 4-nitro-5-styrylisoxazoles for the first time.

Synthesis of a Novel Crown Ether Derived from chiro-Inositol and Its Catalytic Activity on the Asymmetric Michael Addition.

ChemInform ◽  
2003 ◽  
Vol 34 (43) ◽  
Author(s):  
Takahiko Akiyama ◽  
Mikiko Hara ◽  
Kohei Fuchibe ◽  
Shigeru Sakamoto ◽  
Kentaro Yamaguchi
Keyword(s):  
Catalytic Activity ◽  
Crown Ether ◽  
Michael Addition ◽  
Asymmetric Michael Addition

scholarly journals Post-polymerisation modification of bio-derived unsaturated polyester resins via Michael additions of 1,3-dicarbonyls

2016 ◽  
Vol 7 (8) ◽  
pp. 1650-1658 ◽  
Author(s):  
T. J. Farmer ◽  
J. H. Clark ◽  
D. J. Macquarrie ◽  
J. K. Ogunjobi ◽  
R. L. Castle
Keyword(s):  
Michael Addition ◽  
Unsaturated Polyester ◽  
Polyester Resins ◽  
Unsaturated Polyesters ◽  
Unsaturated Polyester Resins ◽  
Michael Additions ◽  
First Time ◽  
The Michael Addition

A rapid (5 min), solventless and heterogeneously catalysed methodology is demonstrated for the first time for the Michael addition of 1,3-dicarbonyls to biomass derived unsaturated polyesters.

scholarly journals Comparison of Cinchona Catalysts Containing Ethyl or Vinyl or Ethynyl Group at Their Quinuclidine Ring

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3034 ◽  
Author(s):  
Nagy ◽  
Fehér ◽  
Dargó ◽  
Barabás ◽  
Garádi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Michael Addition ◽  
Quantum Chemical ◽  
Addition Reaction ◽  
Michael Addition Reaction ◽  
Acid Base ◽  
Ethyl Vinyl ◽  
Ethynyl Group ◽  
Asymmetric Michael Addition ◽  
Vinyl Group

Numerous cinchona organocatalysts with different substituents at their quinuclidine unit have been described and tested, but the effect of those saturation has not been examined before. This work presents the synthesis of four widely used cinchona-based organocatalyst classes (hydroxy, amino, squaramide, and thiourea) with different saturation on the quinuclidine unit (ethyl, vinyl, ethynyl) started from quinine, the most easily available cinchona derivative. Big differences were found in basicity of the quinuclidine unit by measuring the pKa values of twelve catalysts in six solvents. The effect of differences was examined by testing the catalysts in Michael addition reaction of pentane-2,4-dione to trans-β-nitrostyrene. The 1.6–1.7 pKa deviation in basicity of the quinuclidine unit did not result in significant differences in yields and enantiomeric excesses. Quantum chemical calculations confirmed that the ethyl, ethynyl, and vinyl substituents affect the acid-base properties of the cinchona-thiourea catalysts only slightly, and the most active neutral thione forms are the most stable tautomers in all cases. Due to the fact that cinchonas with differently saturated quinuclidine substituents have similar catalytic activity in asymmetric Michael addition application of quinine-based catalysts is recommended. Its vinyl group allows further modifications, for instance, recycling the catalyst by immobilization.

Synthesis of a novel crown ether derived from chiro-inositol and its catalytic activity on the asymmetric Michael addition

2003 ◽  
pp. 1734 ◽  
Author(s):  
Takahiko Akiyama ◽  
Mikiko Hara ◽  
Kohei Fuchibe ◽  
Shigeru Sakamoto ◽  
Kentaro Yamaguchi
Keyword(s):  
Catalytic Activity ◽  
Crown Ether ◽  
Michael Addition ◽  
Asymmetric Michael Addition

scholarly journals Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

2019 ◽  
Vol 15 ◽  
pp. 1289-1297 ◽  
Author(s):  
Alexander N Reznikov ◽  
Anastasiya E Sibiryakova ◽  
Marat R Baimuratov ◽  
Eugene V Golovin ◽  
Victor B Rybakov ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Bioactive Compounds ◽  
Michael Addition ◽  
Michael Reaction ◽  
High Yield ◽  
Michael Adducts ◽  
Significant Rate ◽  
Asymmetric Michael Addition ◽  
Stereogenic Centers ◽  
Asymmetric Michael Reaction

Functionally substituted sulfones with stereogenic centers are valuable reagents in organic synthesis and key motifs in some bioactive compounds. The asymmetric Michael addition of β-ketosulfones to conjugated nitroalkenes in the presence of Ni(II) complexes with various chiral vicinal diamines was studied. This reaction provides convenient access to non-racemic 4-nitro-2-sulfonylbutan-1-ones with two stereocenters with high yield and excellent enantioselectivity (up to 99%). It has been established that the catalytic Michael reaction itself was carried out with high diastereoselectivity, but the Michael adducts may epimerize at the C-2 position at a significant rate. Conditions for the preparation of individual diastereomers were found.

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