Seminars

DEPARTMENT OF CHEMISTRY, SEOUL NATIONAL UNIVERSITY.

RECENT PROGRESS IN THE TOTAL SYNTHESIS OF SOME INDOLE ALKALOIDS

May 31, 2021l Hit 183
Date : June 3, 2021 16:30 ~ 18:00
Speaker : Prof. Cheon-Gyu Cho
Location : ZOOM(Online)

We have previously demonstrated that aryl hydrazides are effective surrogates of aryl hydrazines, undergoing various reactions including the Fischer indole synthesis to afford the corresponding indoles, when treated with enolizable aldehydes and ketones in the presence of an acid. Also reported was that N-Cbz-aryl hydrazide can proceed in a Fischer indolization reaction to give N-Cbz-indole without the elimination of N-Cbz group. Recently, we have found that aryl hydrazide can be directly coupled to vinyl triflate to generate ene-hydrazide, the key intermediate in the Fischer indole synthesis. Heating in the presence of catalytic amount of an acid effected the [3,3]-sigmatropic rearrangement reaction en route to the indole product without scrambling of the regiochemistry, enabling the efficient asymmetric total syntheses of aspidospermidine and tabersonine. This new Fischer indolization base synthetic strategy has been also applied to the synthesis of Strychnos or uleine type alkaloids containing highly strained hexahydro-1,5-methano-1H-azocino[4,3-b]indole core, allowing the asymmetric total syntheses of uleine and tubifolidine. Also presented will be our recent syntheses of some medium-sized ring bearing indole alkaloids including lundurines A-D.


ZOOM(Online) : https://snu-ac-kr.zoom.us/j/85440431357

 

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