An Unusual Rearrangement of Pyrazole Nitrene and Coarctate Ring-Opening/Recyclization Cascade: Formal CH-Acetoxylation and Azide/Amine Conversion without External Oxidants and Reductants

Elena Chugunova; Almir S Gazizov; Daut Islamov; Victoria Matveeva; Alexander Burilov; Nurgali Akylbekov; Alexey Dobrynin; Rakhmetulla Zhapparbergenov; Nurbol Appazov; Beauty K Chabuka; Kimberley Christopher; Daria I Tonkoglazova; Igor V Alabugin

doi:10.3390/molecules28217335

An Unusual Rearrangement of Pyrazole Nitrene and Coarctate Ring-Opening/Recyclization Cascade: Formal CH-Acetoxylation and Azide/Amine Conversion without External Oxidants and Reductants

Molecules. 2023 Oct 30;28(21):7335. doi: 10.3390/molecules28217335.

Authors

Affiliations

¹ Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Akad. Arbuzov St. 8, Kazan 420088, Russia.
² Laboratory of Engineering Profile "Physical and Chemical Methods of Analysis", Korkyt Ata Kyzylorda University, Aitekebie Str. 29A, Kyzylorda 120014, Kazakhstan.
³ Zhakhaev Kazakh Scientific Research Institute of Rice Growing, Abay Av. 25B, Kyzylorda 120008, Kazakhstan.
⁴ Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306-3290, USA.

Abstract

We report an unusual transformation where the transient formation of a nitrene moiety initiates a sequence of steps leading to remote oxidative C-H functionalization (R-CH₃ to R-CH₂OC(O)R') and the concomitant reduction of the nitrene into an amino group. No external oxidants or reductants are needed for this formal molecular comproportionation. Detected and isolated intermediates and computational analysis suggest that the process occurs with pyrazole ring opening and recyclization.

Keywords: 1H-pyrazole; cyclization; fragmentation; furoxan; nitrene.

Abstract

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