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2016.09.20 16:37

[Thu. 22 Sep. 2016] Prof. Anna Lee/Organocatalyzed Asymmetric Reactions

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Speaker Prof. Anna Lee
Date Thursday 22 September 2016
Time 5:00pm
Venue #331, Asan Hall, College of Science

Organocatalyzed Asymmetric Reactions

 

 

The Catalytic Asymmetric Knoevenagel Condensation: The Knoevenagel condensation reaction developed by Emil Knoevenagel in 1896 is a powerful and efficient carbon-carbon bond forming reaction, but also the root of aminocatalysis. Remarkably though, while the Knoevenagel reaction, as the historic basis of all aminocatalyzed processes, has been incorporated into asymmetric organocascades and domino reactions, and even chiral auxiliary derived malonates have been studied, a variation in which the Knoevenagel reaction itself is utilized to establish asymmetry remained elusive. The main problems of the reaction were reactivity and stereoselectivity issues as well as the formation of by-products. The goal of this work was to develop the first enantioselective Knoevenagel condensation reaction using a novel chiral amine catalyst based on a dynamic kinetic resolution (DKR). Various chiral amine catalysts were synthesized, and we found that modified cinchona based amine catalysts provided the desired product in high yield and enantioselectivity.

 

figure.PNG

 

A Cooperative N-Heterocyclic Carbene/Chiral phosphate Catalysis System for Allenolate Annulations: NHC-catalyzed homoenolate additions to various electrophiles represent an enabling class of transformations that have been employed for the construction of complex hetero- and carbocyclic system through unconventional Umpolung reactivity. Recently, our group developed Lewis acid/NHC cooperative catalysis to develope novel transformations. In this study, we have extended the scope of cooperative catalysis by employing chiral phosphoric acids for the first time and this novel cooperative catalysis was applied to the challenging allenolate annulation reaction (Figure 1). A limited number of reports of NHC-catalyzed homoenolate additions involving alkynyl aldehydes have appeared. We have developed a highly efficient asymmetric [3+2] annulation reaction of alkynyl aldehydes withα-ketoesters via NHC/chiral phosphate cooperative catalysis.

 

figure2.PNG

 

 

 

 

References

1. Lee, A.; Michrowska, A.; S.-Mosse, S.; List, B., Angew. Chem. Int. Ed. 2011, 50, 1707.

2. Lee, A.; Reisinger, C.; List, B., Adv. Synth. Catal. 2012, 354, 1701.

3. Lee, A.; Scheidt, K. A., Angew. Chem. Int. Ed. 2014, 53, 7594.

4. Lee, A.; Younai, A. ; Price, C. K. ; Izquierdo, J. ; Mishra, R. K. ; Scheidt, K. A., J. Am. Chem. Soc. 2014,136, 10589.

5. Lee, A.; Scheidt, K. A., Chem. Commun. 2015, 51, 3407.

 

 

Prof. Anna Lee

Myongji University, Department of Chemistry, Yongin, Korea

 

 


List of Articles
No. Subject Speaker Date
Notice Fall semester 2017 Seminar Schedule file - -
43 [Wed. 5 July. 2017] Seminar is canceled! - -
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35 [Thu. 30 Mar. 2017] Prof. Jeong Ho Cho/SKKU Advanced Institute of Nanotechnology (SAINT), School of Chemical Engineering, Sungkyunkwan University, Suwon, Korea Prof. Jeong Ho Cho Thu. 30 Mar. 2017
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31 [Thu. 27 Apr. 2017] Seminar was canceled! - -
30 [Thu. 26 Oct. 2017] Dr. Jung-Nyoung Heo/Center for Medicinal Chemistry Research, Korea Research Institute of Chemical Technology, Daejeon, Korea Dr. Jung-Nyoung Heo Thu. 26 Oct. 2017
29 [Thu. 26 Jun. 2016] Prof. Sung June Cho/Structural Elucidation of Novel Zeolite by Dual Space Approaches Using X-ray Powder Diffraction Prof. Sung June Cho Thursday 26 May 2016
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27 [Thu. 23 Mar. 2017] Prof. Sangsu Bae/Department of Chemistry, Hanyang University, Seoul, South Korea Prof. Sangsu Bae Thu. 23 Mar. 2017
» [Thu. 22 Sep. 2016] Prof. Anna Lee/Organocatalyzed Asymmetric Reactions Prof. Anna Lee Thursday 22 September 2016
25 [Thu. 20 Oct. 2016] Prof. Chan Hyuk Kim/Novel Small Molecule-based Approaches for Cancer Immunotherapy Prof. Chan Hyuk Kim Thursday 20 October 2016
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