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Molecules 2018, 23(3), 674; https://doi.org/10.3390/molecules23030674

Syntheses of 1-Aryl-5-nitro-1H-indazoles and a General One-Pot Route to 1-Aryl-1H-indazoles

Department of Chemistry, Oklahoma State University, Stillwater, OK 74078-3071, USA
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Received: 23 February 2018 / Revised: 13 March 2018 / Accepted: 14 March 2018 / Published: 16 March 2018
(This article belongs to the Collection Heterocyclic Compounds)
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Abstract

An efficient route to substituted 1-aryl-1H-indazoles has been developed and optimized. The method involved the preparation of arylhydrazones from acetophenone or benzaldehyde substituted by fluorine at C2 and nitro at C5, followed by deprotonation and nucleophilic aromatic substitution (SNAr) ring closure in 45–90%. Modification of this procedure to a one-pot domino process was successful in the acetophenone series (73–96%), while the benzaldehyde series (63–73%) required a step-wise addition of reagents. A general one-pot protocol for 1-aryl-1H-indazole formation without the limiting substitution patterns required for the SNAr cyclization has also been achieved in 62–78% yields. A selection of 1-aryl-1H-indazoles was prepared in high yield by a procedure that requires only a single laboratory operation. View Full-Text
Keywords: 1-aryl-5-nitro-1H-indazole; 1-aryl-1H-indazole; arylhydrazone; SNAr reaction; Ullmann reaction 1-aryl-5-nitro-1H-indazole; 1-aryl-1H-indazole; arylhydrazone; SNAr reaction; Ullmann reaction
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Annor-Gyamfi, J.K.; Gnanasekaran, K.K.; Bunce, R.A. Syntheses of 1-Aryl-5-nitro-1H-indazoles and a General One-Pot Route to 1-Aryl-1H-indazoles. Molecules 2018, 23, 674.

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