Catalyst‐Free Site‐Selective Diverse Functionalization of Inherent C–H Bonds in 1‐Aryl‐β‐carbolines, Norharmane and Harmine

A catalyst‐free, site‐selective diverse functionalization of latent C−H bonds in 1‐aryl‐β‐carbolines and natural norharmane and harmine has been accomplished. This method enables the functionalization of 1‐aryl‐β‐carbolines as C6‐chlorination, C6‐bromination, and C4‐nitration employing cost‐effectiv...

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Bibliographic Details
Published in:ChemistrySelect (Weinheim) 2022-08, Vol.7 (29), p.n/a
Main Authors: Soni, Jay Prakash, Kumawat, Akshay, Sathish, Manda, Yadav, Sachin, Jadhav, Nayan Arvind, Shankaraiah, Nagula
Format: Article
Language:English
Subjects:
Bromination
Chlorination
Electrophilic Substitutions
Nitration
β-Carboline
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Summary:A catalyst‐free, site‐selective diverse functionalization of latent C−H bonds in 1‐aryl‐β‐carbolines and natural norharmane and harmine has been accomplished. This method enables the functionalization of 1‐aryl‐β‐carbolines as C6‐chlorination, C6‐bromination, and C4‐nitration employing cost‐effective, eco‐friendly reagents such as trichloroisocyanuric acid (TCCA), N‐bromosuccinimide (NBS) and tert‐butyl nitrite (TBN), respectively. Pleasingly, these catalyst‐/additive‐free strategies were suitable with a broad range of substrate functionalities of different electronic nature, providing moderate to good yields of functionalized 1‐aryl‐β‐carbolines. The critical/sensitive functionalities such as ‐CF3, ‐NO2, ‐CN, and 1‐(thiophen‐2‐yl)‐β‐carboline were successfully employed, offering corresponding C6‐halogenated or C4‐nitrated products without strain. Furthermore, site‐selective chlorination and bromination of two natural alkaloids such as harmine, norharmane were realized, resulting in corresponding halogenated products, including natural product eudistomin‐N. In addition, we also employed these products in further diversification through ‐NO2 reduction and Suzuki (C−C) coupling of brominated compounds to deliver a C6‐arylated product. Herein, we have reported catalyst/additive‐free, site‐selective, diverse functionalization of inherent C−H bonds of 1‐aryl‐β‐carbolines, including natural products norharmane and harmine through chlorination, bromination, and nitration employing trichloroisocyanuric acid (TCCA), N‐bromosuccinimide (NBS) and tert‐butyl nitrite (TBN).
ISSN:2365-6549
2365-6549
DOI:10.1002/slct.202202299