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Straightforward and Efficient Protocol for the Synthesis of Pyrazolo [4,3-b]pyridines and Indazoles.


ABSTRACT: An efficient method for the synthesis of pyrazolo [4,3-b]pyridines has been developed on the basis of readily available 2-chloro-3-nitropyridines via a sequence of SNAr and modified Japp-Klingemann reactions. The method offers a number of advantages including utilization of stable arenediazonium tosylates, operational simplicity as well as combining the azo-coupling, deacylation and pyrazole ring annulation steps in a one-pot manner. An unusual rearrangement (C-N-migration of the acetyl group) was observed and a plausible mechanism was proposed based on the isolated intermediates and NMR experiments. In addition, the developed protocol was successfully applied to the synthesis of 1-arylindazoles combining the Japp-Klingemann reaction and cyclization of the resulting hydrazone as a one-pot procedure.

SUBMITTER: Nikol'skiy VV 

PROVIDER: S-EPMC9860909 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature

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Straightforward and Efficient Protocol for the Synthesis of Pyrazolo [4,3-<i>b</i>]pyridines and Indazoles.

Nikol'skiy Vladislav V VV   Minyaev Mikhail E ME   Bastrakov Maxim A MA   Starosotnikov Alexey M AM  

International journal of molecular sciences 20230116 2


An efficient method for the synthesis of pyrazolo [4,3-<i>b</i>]pyridines has been developed on the basis of readily available 2-chloro-3-nitropyridines via a sequence of SNAr and modified Japp-Klingemann reactions. The method offers a number of advantages including utilization of stable arenediazonium tosylates, operational simplicity as well as combining the azo-coupling, deacylation and pyrazole ring annulation steps in a one-pot manner. An unusual rearrangement (C-N-migration of the acetyl g  ...[more]

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