A highly asymmetric direct aldol reaction catalyzed by chiral proline amide – thiourea bifunctional catalysts

2011 ◽  
Vol 89 (10) ◽  
pp. 1312-1318 ◽  
Author(s):  
Yun Li ◽  
Qing-chuan Yang ◽  
Xiao-Ying Xu ◽  
Yong Zhou ◽  
Jian-fei Bai ◽  
...  

A series of chiral proline amide – thiourea bifunctional catalysts derived from l-proline and chiral diamine were prepared and successfully applied to highly enantioselective direct aldol reactions of cyclohexanone with various aldehydes in excellent yields (85%–97%), diastereoselectivities (anti/syn > 20:1) and enantioselectivities (up to 91% ee).

2019 ◽  
Vol 6 (2) ◽  
pp. 171-176
Author(s):  
Rajasekhar Dodda ◽  
Sampak Samanta ◽  
Matthew Su ◽  
John Cong-Gui Zhao

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.


2003 ◽  
Vol 44 (30) ◽  
pp. 5699-5701 ◽  
Author(s):  
Michael A. Calter ◽  
Robert K. Orr

2020 ◽  
Vol 44 (44) ◽  
pp. 19288-19293
Author(s):  
Sergio Rossi ◽  
Maurizio Benaglia ◽  
Laura Maria Raimondi

The stereoselective organocatalytic addition of silyl enol ethers to aromatic aldehydes catalyzed by bisphosphoramides and the direct aldol reaction between ketones and aromatic aldehydes promoted by phosphinoxides in the presence of tetrachlorosilane were investigated by the DFT approach.


2015 ◽  
Vol 13 (16) ◽  
pp. 4795-4802 ◽  
Author(s):  
Tony K. M. Shing ◽  
Hau M. Cheng

A regio- and stereoselective intramolecular direct aldol reaction of 2,7-diketones derived from carbohydrates has been developed to construct cycloalkanones 7, which were dehydrated to obtain heavily oxygenated cycloalkenones 8.


ChemInform ◽  
2003 ◽  
Vol 34 (42) ◽  
Author(s):  
Michael A. Calter ◽  
Robert K. Orr

Synlett ◽  
2017 ◽  
Vol 28 (11) ◽  
pp. 1363-1367 ◽  
Author(s):  
Tsuyoshi Miura ◽  
Hiroshi Akutsu ◽  
Kosuke Nakashima ◽  
Hikaru Yanai ◽  
Akira Kotani ◽  
...  

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.


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

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