Synthesis 2022; 54(07): 1793-1802
DOI: 10.1055/a-1684-0308
paper

Halogenations of 3-Aryl-1H-pyrazol-5-amines

Jing He
,
Yueting Wei
,
Yijiao Feng
,
Chuntian Li
,
Bin Dai
,
Ping Liu
We gratefully acknowledge financial support of this work by the National Natural Science Foundation of China (No. 21563025).


Abstract

A direct C–H halogenation of 3-aryl-1H-pyrazol-5-amines using N-halogenosuccinimides (NXS; X = Br, I, Cl) in dimethyl sulfoxide at room temperature has been developed. This transformation provides an effective metal-free protocol for the synthesis of novel 4-halogenated pyrazole derivatives with moderate to excellent yields. The method utilizes NXS reagents as cheap and safe halogenating reagents under simple and mild reaction conditions, it has broad substrate scope, and can be used for gram-scale synthesis. The utility of this procedure is established by further transformations of the 4-halogenated products. Mechanism studies show that DMSO plays a dual role of catalyst and solvent.

Supporting Information



Publication History

Received: 12 October 2021

Accepted after revision: 02 November 2021

Accepted Manuscript online:
02 November 2021

Article published online:
06 December 2021

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