Issue 22, 2020

Triarylborane catalysed N-alkylation of amines with aryl esters


The ability of halogenated triarylboranes to accept a lone pair of electrons from donor substrates renders them excellent Lewis acids which can be exploited as a powerful tool in organic synthesis. Tris(pentafluorophenyl)borane has successfully demonstrated its ability to act as a metal-free catalyst for an ever-increasing range of organic transformations. Herein we report the N-alkylation reactions of a wide variety of amine substrates including diarylamines, N-methylphenyl amines, and carbazoles with aryl esters using catalytic amounts of B(C6F5)3. This mild reaction protocol gives access to N-alkylated products (35 examples) in good to excellent yields (up to 95%). The construction of a C–N bond at the propargylic position has also been demonstrated to yield synthetically useful propargyl amines. On the other hand, unsubstituted 1H-indoles and 1H-pyrroles at the C3/C2 positions afforded exclusively C–C coupled products. Extensive DFT studies have been employed to understand the mechanism for this transformation.

Graphical abstract: Triarylborane catalysed N-alkylation of amines with aryl esters

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Article information

Article type
03 Jul 2020
15 Sep 2020
First published
16 Sep 2020
This article is Open Access
Creative Commons BY license

Catal. Sci. Technol., 2020,10, 7523-7530

Triarylborane catalysed N-alkylation of amines with aryl esters

V. Nori, A. Dasgupta, R. Babaahmadi, A. Carlone, A. Ariafard and R. L. Melen, Catal. Sci. Technol., 2020, 10, 7523 DOI: 10.1039/D0CY01339K

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