Copper-mediated oxidative [3 + 2]-annulation of nitroalkenes and pyridinium imines: efficient synthesis of 3-fluoro- and 3-nitro-pyrazolo[1,5-a]pyridines

Copper-mediated oxidative [3 + 2]-annulation of nitroalkenes and pyridinium imines: efficient synthesis of 3-fluoro- and 3-nitro-pyrazolo[1,5-a]pyridines Full article

Journal

Organic & Biomolecular Chemistry
ISSN: 1477-0520 , E-ISSN: 1477-0539

Output data

Year: 2020, Volume: 18, Number: 7, Pages: 1436-1448 Pages count : 13 DOI: 10.1039/c9ob02668a

Authors

Motornov Vladimir A. ^1,2 , Tabolin Andrey A. ¹ , Nelyubina Yulia V. ³ , Nenajdenko Valentine G. ⁴ , Ioffe Sema L. ¹

Affiliations

1	N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prosp. 47, Moscow, Russia
2	Higher Chemical College, D. I. Mendeleev University of Chemical Technology of Russia, Miusskaya sq. 9, Moscow, 125047, Russia
3	A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str. 28, Moscow, Russia
4	Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119991, Russia

An efficient route to pyrazolo[1,5-a]pyridines by Cu(OAc)2-promoted oxidative [3 + 2]-annulation of nitroalkenes with in situ generated pyridinium imines is developed. The reaction with α-fluoronitroalkenes enables the first preparative synthesis of 3-fluoro-pyrazolo[1,5-a]pyridines. Cycloaddition with α-unsubstituted nitroalkenes provides access to 3-nitro-pyrazolo[1,5-a]pyridines in excellent yields. A broad transformation scope was demonstrated. Both electron-rich and electron-deficient nitroalkenes as well as different aminopyridinium salts can be used for the assembly of the target pyrazolo[1,5-a]pyridines. The related aza-heterocycles, namely, pyrazolo[1,5-a]pyrazines and pyrazolo[1,5-b]pyridazines, were successfully prepared via the present methodology. The possible mechanism of the reaction is discussed.

Motornov V.A. , Tabolin A.A. , Nelyubina Y.V. , Nenajdenko V.G. , Ioffe S.L.
Copper-mediated oxidative [3 + 2]-annulation of nitroalkenes and pyridinium imines: efficient synthesis of 3-fluoro- and 3-nitro-pyrazolo[1,5-a]pyridines
Organic & Biomolecular Chemistry. 2020. V.18. N7. P.1436-1448. DOI: 10.1039/c9ob02668a WOS Scopus OpenAlex

≡ Web of science:	WOS:000517113000015
≡ Scopus:	2-s2.0-85080841807
≡ OpenAlex:	W3002892446