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

Autor: Nikol'skiy VV; N.D. Zelinsky Institute of Organic Chemistry RAS, Leninsky Prosp. 47, 119991 Moscow, Russia., Minyaev ME; N.D. Zelinsky Institute of Organic Chemistry RAS, Leninsky Prosp. 47, 119991 Moscow, Russia., Bastrakov MA; N.D. Zelinsky Institute of Organic Chemistry RAS, Leninsky Prosp. 47, 119991 Moscow, Russia., Starosotnikov AM; N.D. Zelinsky Institute of Organic Chemistry RAS, Leninsky Prosp. 47, 119991 Moscow, Russia.
Jazyk: angličtina
Zdroj: International journal of molecular sciences [Int J Mol Sci] 2023 Jan 16; Vol. 24 (2). Date of Electronic Publication: 2023 Jan 16.
DOI: 10.3390/ijms24021758
Abstrakt: 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.
Databáze: MEDLINE
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