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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 Fall semester 2017 Seminar Schedule file - -
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 file - 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 file - -
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
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
8 [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 file - -
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
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