|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
|Notice||Fall semester 2017 Seminar Schedule||-||-|
|29||[Thu. 1 Jun. 2017] Prof. Jong-Man Kim/Department of Chemical Engineering, Hanyang University, Seoul, Korea||Prof. Jong-Man Kim||Thu. 1 Jun. 2017|
|28||[Thu. 25 May. 2017] Prof. Wonsuk Kim/Department of Chemistry and Nano Science, Ewha Womans University, Seoul||Prof. Wonsuk Kim||Thu. 25 May. 2017|
|27||[Thu. 18 May. 2017] Student Host Colloquium : 1,1-Bisborylalkane: New Class of Organoboron Compound for the Chemo, Regio and Stereoselective Organic Transformations||Prof. Seung Hwan Cho||Thu. 18 May. 2017|
|26||[Thu. 11 May. 2017] Prof. Andreas Heinrich/IBS Research, Center for Quantum Nanoscience, Seoul, South Korea||Prof. Andreas Heinrich||Thu. 11 May. 2017|
|25||[Thu. 27 Apr. 2017] Seminar was canceled!||-||-|
|24||[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|
|23||[Thu. 6 Apr. 2017] Prof. Rong-Jie Chein/Institute of Chemistry, Academia Sinica, Nankang, Taipei, Taiwan||Prof. Rong-Jie Chein||Thu. 6 Apr. 2017|
|22||[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|
|21||[Thu. 23 Mar. 2017] Prof. Sangsu Bae/Department of Chemistry, Hanyang University, Seoul, South Korea||Prof. Sangsu Bae||Thu. 23 Mar. 2017|
|20||[Fri. 17 Mar. 2017] 9th RINS Symposium||-||Fri. 17 Mar. 2017|
|19||[Thu. 9 Mar. 2017] Prof. Woon Ju Song/Department of Chemistry, Seoul National University, Seoul, Korea||Prof. Woon Ju Song||Thu. 9 Mar. 2017|
|18||Spring semester 2017 Seminar Schedule||-||-|
|17||[Mon. 9 Jan. 2017] Prof. Sungwook Woo/Wyss Institute for Biologically Inspired Engineering, Harvard University, USA||Prof. Sungwook Woo||Mon. 9 Jan. 2017|
|16||[Wed. 28 Dec. 2016] Prof. James Y. Hamilton/Development of a Broad Range of Asymmetric C–C Bond Forming Reactions with a Versatile Iridium Catalyst||Prof. James Y. Hamilton||Wednesday 28 December 2016|
|15||[Thu. 1 Dec. 2016] Prof. Sang-Yong Ju/Highly Pure Carbon Nanotubes sorted by a Flavin for Thin Film Transistor Applications||Prof. Sang-Yong Ju||Thursday 1 December 2016|
|14||[Thu. 17 Nov. 2016] Prof. Seunghoon Shin/Synthetic Methods Development based on Rational Analysis of Intermediates||Prof. Seunghoon Shin||Thursday 17 November 2016|
|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|
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