ChemInform Abstract: L-Proline-Catalyzed Asymmetric Direct Aldol Reaction of Heteroaromatic Aldehydes and Acetone: Improvement of Catalytic Efficiency in Ionic Liquid bmim [BF4].

ChemInform ◽  
2008 ◽  
Vol 39 (18) ◽  
Author(s):  
K. Rajender Reddy ◽  
L. Chakrapani ◽  
T. Ramani ◽  
C. V. Rajasekhar
Keyword(s):  
Ionic Liquid ◽  
Aldol Reaction ◽  
Catalytic Efficiency ◽  
Direct Aldol Reaction

Organocatalytic Asymmetricsyn-Selective Direct Aldol Reaction in Ionic Liquid

2010 ◽  
Vol 39 (5) ◽  
pp. 490-492 ◽  
Author(s):  
Fui-Fong Yong ◽  
Chai-Yun Poh ◽  
Guan-Leong Chua ◽  
Yong-Chua Teo
Keyword(s):  
Ionic Liquid ◽  
Aldol Reaction ◽  
Direct Aldol Reaction

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.

ChemInform Abstract: Organocatalytic Asymmetric syn-Selective Direct Aldol Reaction in Ionic Liquid.

ChemInform ◽  
2010 ◽  
Vol 41 (42) ◽  
Author(s):  
Fui-Fong Yong ◽  
Chai-Yun Poh ◽  
Guan-Leong Chua ◽  
Yong-Chua Teo
Keyword(s):  
Ionic Liquid ◽  
Aldol Reaction ◽  
Direct Aldol Reaction

Synthesis of novel chiral bithiophenebased phosphine oxides as Lewis bases in organocatalytic stereoselective reactions

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Sergio Rossi ◽  
Maurizio Benaglia ◽  
Roberto Cirilli ◽  
Tiziana Benincori
Keyword(s):  
Phosphine Oxide ◽  
Aldol Reaction ◽  
Enantiomeric Excess ◽  
Catalytic Efficiency ◽  
Phosphine Oxides ◽  
Aromatic Rings ◽  
Enantiomerically Pure ◽  
Lewis Bases ◽  
Direct Aldol Reaction ◽  
Stereoselective Reactions

Abstract Novel enantiomerically pure tetramethylbithiophene diphosphine oxides (tetraMe-BITIOPO) featuring differently substituted aromatic rings at the phosphorous atoms were synthesized, fully characterized and isolated in enantiomerically pure form. The new Lewis bases were tested as organocatalysts in two different reactions involving trichlorosilyl compounds. The introduction of electron donating substituents on the aromatic rings connected to the phosphine oxide groups positively affected the chemical and stereochemical catalytic efficiency of these ligands. The new catalysts were able to promote the allylation of aldehydes with allyltrichlorosilane in up to 76% yield and up to 86% enantiomeric excess (ee), and the direct aldol reaction to afford β-hydroxy ketones in high diastereoselectivity (up to 88:12 anti:syn ratio) and up to 72% ee.

scholarly journals RuCl3 · nH2O as Catalyst for Diastereoselective Direct Aldol Reaction: An Efficient Route to Hormone Steroid Derivatives

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
Khalil Tabatabaeian ◽  
Elahe Keshavarz ◽  
Manouchehr Mamaghani ◽  
Nosrat O. Mahmoodi
Keyword(s):  
Aldol Reaction ◽  
Reaction Times ◽  
Catalytic Efficiency ◽  
Aromatic Aldehydes ◽  
Direct Aldol Reaction ◽  
Efficient Route

-catalyzed regio- and diastereoselective direct aldol reaction of progesterone with aromatic aldehydes has been developed in good yields (58–78%). Advantages of this method include catalytic efficiency, short reaction times, and ease of operation and workup.

Ionic liquid supported acid additive stabilizes the transition structure of organocatalytic asymmetric direct aldol reaction by proton donation: A quantum mechanical study

2016 ◽  
Vol 15 (06) ◽  
pp. 1650049 ◽  
Author(s):  
Kuheli Chakrabarty ◽  
Atanu Basak ◽  
Animesh Ghosh ◽  
Gourab Kanti Das
Keyword(s):  
Ionic Liquid ◽  
Benzoic Acid ◽  
Significant Role ◽  
Aldol Reaction ◽  
Proton Donor ◽  
Quantum Mechanical ◽  
Transition Structure ◽  
Direct Aldol Reaction ◽  
Mechanical Study ◽  
Quantum Mechanical Study

ONIOM studies were performed on the transition structure (TS) of organocatalytic direct aldol reaction by using ionic liquid supported benzoic acid (ILS-PhCO2H) as an additive. Results obtained from this computation suggest direct involvement of ILS-PhCO2H in the TS as a proton donor. It has also come out from the present study that, the counter ion of the ILS-acid additive may also play significant role to maintain the proper TS geometry by holding the organocatalyst and the acid additive close together during the course of reaction.

scholarly journals Simple and fast microwave-assisted ruthenium_catalyzed direct aldol reaction

2012 ◽  
Vol 1 (2) ◽  
pp. 91-94 ◽  
Author(s):  
Elahe Keshavarz ◽  
Khalil Tabatabaeian ◽  
Manouchehr Mamaghani ◽  
Nosrat O. Mahmoodi
Keyword(s):  
Aldol Reaction ◽  
Microwave Assisted ◽  
Direct Aldol Reaction
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