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. 2021 Nov 22;60(48):25252-25257.
doi: 10.1002/anie.202110304. Epub 2021 Oct 25.

Cooperative NHC/Photoredox Catalyzed Ring-Opening of Aryl Cyclopropanes to 1-Aroyloxylated-3-Acylated Alkanes

Zhijun Zuo  1 , Constantin G Daniliuc  1 , Armido Studer  1
Affiliations

Cooperative NHC/Photoredox Catalyzed Ring-Opening of Aryl Cyclopropanes to 1-Aroyloxylated-3-Acylated Alkanes

Zhijun Zuo et al. Angew Chem Int Ed Engl. .

Abstract

Cyclopropanes are an important class of building blocks in organic synthesis. Herein, a ring-opening/arylcarboxylation/acylation cascade reaction for the 1,3-difunctionalization of aryl cyclopropanes enabled by cooperative NHC and organophotoredox catalysis is reported. The cascade works on monosubstituted cyclopropanes that are in contrast to the heavily investigated donor-acceptor cyclopropanes more challenging to be difunctionalized. The key step is a radical/radical cross coupling of a benzylic radical generated in the photoredox catalysis cycle with a ketyl radical from the NHC catalysis cycle. The transformation features metal-free reaction conditions and tolerates a diverse range of functionalities.

Keywords: N-heterocyclic carbenes; cascade reactions; cyclopropanes; photoredox catalysis; reaction mechanisms.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Ionic, transition‐metal‐catalyzed and radical 1,3‐difunctionalization of cyclopropanes.
Scheme 2
Scheme 2
Variation of the acyl fluoride component.
Scheme 3
Scheme 3
Variation of the cyclopropane component.
Scheme 4
Scheme 4
Large scale experiment and follow‐up transformations. (I) NaOH, THF/H2O, 80 °C; (II) LiAlH4 (5 equiv), THF, 0 °C–rt; (III) TfOH (10 mol %), 1,2‐DCE, 40 °C.
Scheme 5
Scheme 5
Mechanistic studies and proposed mechanism.
Scheme 6
Scheme 6
Ring‐opening of aryl cyclopropanes with anhydrides.
See this image and copyright information in PMC

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