Issue 6, 2024

Ru(ii)-catalyzed regioselective [4 + 1] redox-neutral spirocyclization of aryl amidines with diazopyrazolones: direct access to spiro[indole-3,4′-pyrazol]-5′-ones

Abstract

An efficient protocol to construct spiro[indole-3,4′-pyrazol]-5′-ones via ruthenium(II)-catalyzed selective C–H bond activation/[4 + 1] spirocyclization starting from easily available N-aryl amidines and diazopyrazolones has been developed. A series of spiropyrazolones could be easily obtained under mild reaction conditions with high step and atom economy. Mechanistically, the formation of spirocycles involves Ru(II)-catalyzed C(sp2)–H bond cleavage, metal carbene formation, migratory insertion, intramolecular nucleophilic addition, and elimination. This protocol features obviating the use of external oxidants, excellent regioselectivity and broad generality of substrates.

Graphical abstract: Ru(ii)-catalyzed regioselective [4 + 1] redox-neutral spirocyclization of aryl amidines with diazopyrazolones: direct access to spiro[indole-3,4′-pyrazol]-5′-ones

Supplementary files

Article information

Article type
Research Article
Submitted
16 Dec 2023
Accepted
21 Jan 2024
First published
25 Jan 2024

Org. Chem. Front., 2024,11, 1811-1816

Ru(II)-catalyzed regioselective [4 + 1] redox-neutral spirocyclization of aryl amidines with diazopyrazolones: direct access to spiro[indole-3,4′-pyrazol]-5′-ones

B. Cui, J. Shen, Y. Feng, S. Lin and X. Cui, Org. Chem. Front., 2024, 11, 1811 DOI: 10.1039/D3QO02071A

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