|Speaker||Prof. Anna Lee|
|Date||Thursday 22 September 2016|
|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.
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.
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
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|54||[Fri. 17 Mar. 2017] 9th RINS Symposium||-||Fri. 17 Mar. 2017|
|53||Spring semester 2017 Seminar Schedule||-||-|
|52||Fall semester 2017 Seminar Schedule||-||-|
|51||[Thu. 27 Apr. 2017] Seminar was canceled!||-||-|
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|49||7th Jilin-Korea-Waseda Alliance Annual Symposium||-||August 17 ~ 19, 2017|
|48||[October 10, 2017] Novel Terahertz Spectroscopies||Director Mischa Bonn||Tue, October 10, 2017|
|47||[October 25, 2017] Ultrafast electron microscopy: applications in chemical and materials sciences||Dr. Byung-Kuk Yoo||October 25, 2017|
|46||[March 5. 2019] Innovation@Agilent||Dr. Darlene Solomon (Agilent Technologies Inc.)||Tuesday. 5 March. 2019|
|45||[Fri. 13 Oct. 2017] Dr. J. Nathan Hohman/The Molecular Foundry, Lawrence Berkeley National Laboratory, California, USA||Dr. J. Nathan Hohman||Fri. 13 Oct. 2017|
|44||[March 20, 2019] Challenges in molecular dynamics simulations of unfolded proteins and protein-DNA complexes||Dr. Jejoong Yoo||March 20, 2019|
|43||[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|
|42||[Thu. 13 Apr. 2017] Dr. Wan Ki Bae/Photoelectronic Hybrid Research Center, Korea Institute of Science and Technology, Seoul, Korea||Dr. Wan Ki Bae||Thu. 13 Apr. 2017|
|41||[Mon. 13 Oct. 2016] Prof. Amir H. Hoveyda/Multicomponent Catalytic Synthesis of Organoboron Compounds for Scalable Natural Product Synthesis||Prof. Amir H. Hoveyda||Monday 13 October 2016|
|40||[Thu. 11 May. 2017] Prof. Andreas Heinrich/IBS Research, Center for Quantum Nanoscience, Seoul, South Korea||Prof. Andreas Heinrich||Thu. 11 May. 2017|
|»||[Thu. 22 Sep. 2016] Prof. Anna Lee/Organocatalyzed Asymmetric Reactions||Prof. Anna Lee||Thursday 22 September 2016|
|38||[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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