|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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|Notice||Spring semester 2017 Seminar Schedule||-||-|
|13||[Thu. 3 Nov. 2016] Prof. Min-Sik Kim/Mass spectrometry and its applications to Biological Discovery||Prof. Min-Sik Kim||Thursday 3 November 2016|
|12||[Thu. 20 Oct. 2016] Prof. Chan Hyuk Kim/Novel Small Molecule-based Approaches for Cancer Immunotherapy||Prof. Chan Hyuk Kim||Thursday 20 October 2016|
|11||[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|
|10||[Thu. 6 Oct. 2016] Prof. Young S. Park/Atomistic Molecular Engineering of Polycyclic Aromatic Hydrocarbons||Prof. Young S. Park||Thursday 6 October 2016|
|9||[Thu. 29 Sep. 2016] Prof. Tae-Young Yoon/Observation of Single Membrane Proteins under Mechanical Tension||Prof. Tae-Young Yoon||Thursday 29 September 2016|
|»||[Thu. 22 Sep. 2016] Prof. Anna Lee/Organocatalyzed Asymmetric Reactions||Prof. Anna Lee||Thursday 22 September 2016|
|7||[Thu. 8 Sep. 2016] Prof. Jaeyoung Sung/Stochastic chemical dynamics in living cells and its consequence for the control capacity of living cells over biological functions||Prof. Jaeyoung Sung||Thursday 8 September 2016|
|6||Fall semester 2016 Seminar Schedule||-||-|
|5||[Fri. 17 Jun. 2016] Prof. Jianwei Sun/Remote Control in Brønsted Acid Catalysis: New Strategies for the Synthesis of Chiral Building Blocks and Medium Rings||Prof. Jianwei Sun||Friday 17 June 2016|
|4||[Thu. 9 Jun. 2016] Prof. Yong-Young Noh/Development of Printed Large Area Organic Transistors and Integrated Circuits||Prof. Yong-Young Noh||Thursday 9 June 2016|
|3||[Thu. 2 Jun. 2016] Prof. Sunkyu Han/Total Syntheses of Complex Alkaloids Inspired by Biosynthetic Hypotheses||Prof. Sunkyu Han||Thursday 2 June 2016|
|2||[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|
|1||[Thu. 19 May. 2016] Prof. Zhuang Liu/Nanotechnology for enhanced cancer radiation therapy and immunotherapy||Prof. Zhuang Liu||Thursday 19 May 2016|
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