|Speaker||Prof. Sung-Gon Kim|
|Date||Thu. 23 Nov. 2017|
|Venue||#331, Asan Hall, College of Science|
“Organocatalytic Cascade Reactions for the Asymmetric Synthesis
of Fused-ring Compounds”
Fused-ring structural units including chroman, indoline, pyrrolidine and hydroqunoline are widely distributed in nature and many biologically active compounds. Molecules containing these structural units exhibit a broad range of bioactivities such as anticancer, antiviral, antitumar, antimicrobial, sex pheromone, and central nervous system activity. Owing to the importance of these class of compounds, the stereoselective synthesis of fused-ring compounds is a noteworthy synthetic goal. In this presentation, we demonstrate the asymmetric synthesis of hydroquinoline, hydroquinazoline, and indolines via catalytic cascade reaction.
First, A synthetic method for the construction of fully substituted enantioenriched 1,4-dihydroquinolines using an organocatalytic aza-Michael/Michael cascade reaction has been developed (Sheme 1). 1 The asymmetric reaction of 2-(tosylamino)phenyl α,β-unsaturated ketones with alkynyl aldehydes, promoted by diphenylprolinol O-TMS ether as an organocatalyst, generated chiral 1,4-dihydroquinolines in good to high yields with excellent enantioselectivities (up to 97% ee)
We have also found a concise synthetic route to valuable highly functionalized benzosulfamidate-fused tetrahydroquinazoline (Scheme 2).2 The [4+2] cycloaddition of o-N-Cbz-amino-b-nitrostyrene with benzoxathiazine 2,2-dioxide using an imidazole as the catalyst afforded tetrahydroquinazolines with high diastereoselectivities.
In addition, we have established the synthesis of chiral benzosulfamidate-fused pyrrolidines through an Mannich/aza-Michael cascade reaction of δ-formyl-a,b-unsaturated ketones with cyclic N-sulfimines (Scheme 3).3 This simple domino process afforded diverse highly functionalized pyrrolidines in good yields with high diastero- and enantioselectivities.
1. Lee, Y.; Heo, S.; Kim, S.-G. Adv. Synth. Catal. 2015, 357, 1545-1550.
2. Sim, J.-T.; Kim, H. Kim, S.-G. Tetrahedron Lett. 2016, 57, 5907-5910.
3. Kim, H.; Kim, Y.; Kim, S.-G. J. Org. Chem. 2017, 82, 8179-8185.
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|Notice||Fall semester 2017 Seminar Schedule||-||-|
|9||[October 25, 2017] Ultrafast electron microscopy: applications in chemical and materials sciences||Dr. Byung-Kuk Yoo||October 25, 2017|
|8||[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|
|7||[October 31, 2017] New ways of vision: Protein structures in translational medicine and business development, my experience||Prof. Robert Huber(1988 Nobel Prize in Chemistry)||October 31, 2017|
|6||[Fri. 30 Oct. 2017] Prof. Igor Rodin/Department of Chemistry, Moscow State University, Moscow, Russia||Prof. Igor Rodin||Fri. 30 Oct. 201|
|5||[Thu. 16 Nov. 2017] Prof. Hyungjun Kim/Department of Chemistry, and Graduate school of Energy, Environment, Water, and Sustainability (EEWS), KAIST, Daejeon, Korea||Prof. Hyungjun Kim||Thu. 16 Nov. 2017|
|4||[November 14, 2017] Zero-Point Energy, Fluctuations, and Dissipation : A (Mostly) Quantum-Optical Perspective||Prof. Milonni, Peter||November 14, 2017|
|»||[Thu. 23 Nov. 2017] Prof. Sung-Gon Kim/Department of Chemistry, Kyonggi University, Suwon, Korea||Prof. Sung-Gon Kim||Thu. 23 Nov. 2017|
|2||[Thu. 30 Nov. 2017] Prof. Sunmin Ryu/Department of Chemistry, POSTECH, Pohang, South Korea||Prof. Sunmin Ryu||Thu. 30 Nov. 2017|
|1||[January 24, 2018] Electro-Optic Organic THz Wave Sources||Prof. O-Pil Kwon(Ajou University)||January 24, 2018 (Wednesday)|
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