Issue 32, 2024

C–H functionalization of 2-alkyl tryptamines: direct assembly of azepino[4,5-b]indoles and total synthesis of ngouniensines

Abstract

The Pictet–Spengler type condensation of tryptamine derivatives and aldehydes or ketones is a classic reaction, and has been previously applied to assemble indole-annulated 5-, 6- and 8-membered heterocyclic rings. In this work, we further expand the synthetic scope of this reaction to the 7-membered azepino[4,5-b]indole skeleton through the direct C–H functionalization of 2-alkyl tryptamines, in which the non-activated methylene group participates in a 7-membered ring formation with aldehydes. By combining this unprecedented ring-forming process with a second C–H olefination at the same carbon, the concise total synthesis of natural products ngouniensines is achieved, demonstrating the synthetic potential of the developed chemistry in simplifying retrosynthetic disconnections.

Graphical abstract: C–H functionalization of 2-alkyl tryptamines: direct assembly of azepino[4,5-b]indoles and total synthesis of ngouniensines

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Article information

Article type
Edge Article
Submitted
28 Apr 2024
Accepted
05 Jul 2024
First published
05 Jul 2024
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2024,15, 12732-12738

C–H functionalization of 2-alkyl tryptamines: direct assembly of azepino[4,5-b]indoles and total synthesis of ngouniensines

K. Xie, Z. Shen, P. Cheng, H. Dong, Z. Yu and L. Zu, Chem. Sci., 2024, 15, 12732 DOI: 10.1039/D4SC02802C

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