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2016.11.15 11:21

[Thu. 17 Nov. 2016] Prof. Seunghoon Shin/Synthetic Methods Development based on Rational Analysis of Intermediates

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Speaker Prof. Seunghoon Shin
Date Thursday 17 November 2016
Time 5:00pm
Venue #331, Asan Hall, College of Science

“Synthetic Methods Development based on 

Rational Analysis of Intermediates”

 

Proper analysis and identification of reaction intermediates in catalysis often lead to new reaction discovery. In this presentation, we describe some of our recent investigations in the gold and Brőnsted acid catalysis. Allenols are found to be transient intermediates in the gold-catalyzed Meyer-Schuster rearrangement of propargyl alcohols en route to enones. In our tandem Meyer-Schuster rearrangement and ring expansion (eq. 1),1 the allenol intermediates play key roles in the diastereo- and enantioselective ring expansion of cyclobutanols having a butyne-1,4-diol unit into cyclopentanones. A related allenol intermediate could also be utilized in the context of cross-coupling chemistry. Compared to the dual Au-photoredox cross-coupling of C(sp3)-Au intermediates,2a the corresponding cross-coupling of C(sp2)-Au species for the formation of C(sp2)- C(sp2) coupling is more challenging, due to a facile proto-demetallation of C(sp2)-Au bond. The Au(I)-Au(III) cycle enabled under the photoredox condition is fast enough to outcompete this undesired side pathway (eq. 2).2b-c This protocol is catalytic both in gold- and photocatalyst and utilizes diazoniums for the dual role of external oxidant and coupling partner. Lastly, oxygenative cross-coupling of alkynes has received tremendous growth, as it obviates the use of diazo precursors. Yet, a concrete support for the involvement of Au-carbene species is still lacking and, especially, intermolecular coupling is very rare. Using Brőnsted acid as a catalytic promotor instead of Au-complex, this transformation occurs under exceptionally mild conditions allowing couplings of diverse nucleophiles (eq. 3). In addition, a SN2’ mechanism could be supported by the formation of scalemic products when chiral N-oxides were used.

 

 

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References

1. An, J. -H.; Yun, H.; Shin, S.; Shin, S., Adv. Synth. Catal. 2014, 356, 3749.

2. (a) Sahoo, B.; Hopkinson, M. N.; Glorius, F. J. Am. Chem. Soc. 2013, 135, 5505; (b) Patil, D. V.; Yun, H.; Shin, S. Adv. Synth. Catal. 2015, 357, 2622; (c) Um, J.; Yun, H.; Shin, S. Org. Lett. 2016,18, 484.

3. Unpublished results, Patil, D. V.; Kim, S. 

 

Prof. Seunghoon Shin

Department of Chemistry, Hanyang University, South Korea


List of Articles
No. Subject Speaker Date
Notice Spring semester 2017 Seminar Schedule file - -
32 7th Jilin-Korea-Waseda Alliance Annual Symposium file - August 17 ~ 19, 2017
31 [Wed. 5 July. 2017] Seminar was canceled! - -
30 [Fri. 16 Jun. 2017] Prof. Martin Thuo/Department of Materials Science and Engineering, Iowa State University, USA Prof. Martin Thuo Fri. 16 Jun. 2017
29 [Thu. 8 Jun. 2017] Prof. Won-jin Chung/Department of Chemistry, GIST, Gwangju, Republic of Korea Prof. Won-jin Chung Thu. 8 Jun. 2017
28 [Thu. 1 Jun. 2017] Prof. Jong-Man Kim/Department of Chemical Engineering, Hanyang University, Seoul, Korea Prof. Jong-Man Kim Thu. 1 Jun. 2017
27 [Thu. 25 May. 2017] Prof. Wonsuk Kim/Department of Chemistry and Nano Science, Ewha Womans University, Seoul Prof. Wonsuk Kim Thu. 25 May. 2017
26 [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
25 [Thu. 11 May. 2017] Prof. Andreas Heinrich/IBS Research, Center for Quantum Nanoscience, Seoul, South Korea Prof. Andreas Heinrich Thu. 11 May. 2017
24 [Thu. 27 Apr. 2017] Seminar was canceled! - -
23 [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
22 [Thu. 6 Apr. 2017] Prof. Rong-Jie Chein/Institute of Chemistry, Academia Sinica, Nankang, Taipei, Taiwan Prof. Rong-Jie Chein Thu. 6 Apr. 2017
21 [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
20 [Thu. 23 Mar. 2017] Prof. Sangsu Bae/Department of Chemistry, Hanyang University, Seoul, South Korea Prof. Sangsu Bae Thu. 23 Mar. 2017
19 [Fri. 17 Mar. 2017] 9th RINS Symposium file - Fri. 17 Mar. 2017
18 [Thu. 9 Mar. 2017] Prof. Woon Ju Song/Department of Chemistry, Seoul National University, Seoul, Korea Prof. Woon Ju Song Thu. 9 Mar. 2017
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 file 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
» [Thu. 17 Nov. 2016] Prof. Seunghoon Shin/Synthetic Methods Development based on Rational Analysis of Intermediates file Prof. Seunghoon Shin Thursday 17 November 2016
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