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. 2020 Dec 18;22(24):9524-9528.
doi: 10.1021/acs.orglett.0c03581. Epub 2020 Dec 2.

Copper Catalyzed Oxidative Arylation of Tertiary Carbon Centers

Prakash Basnet  1 , Melissa B Sebold  1 , Charles E Hendrick  1 , Marisa C Kozlowski  1
Affiliations

Copper Catalyzed Oxidative Arylation of Tertiary Carbon Centers

Prakash Basnet et al. Org Lett. .

Abstract

We describe herein a Cu(OTf)2 catalyzed oxidative arylation of a tertiary carbon-containing substrate including aryl malononitriles, 3-aryl benzofuran-2-ones, and 3-aryl oxindoles. In some cases, the nitrile groups of the aryl malononitriles undergo further reactions leading to lactones or imines. These reaction conditions are applicable for a range of arenes, including phenols, anilines, anisoles, and heteroarenes. Mechanistic studies support the formation of a cationic intermediate via a two-electron oxidation.

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Figures

Figure 1.
Figure 1.
Selected bioactive compounds containing 3-aryl-substituted benzofuran-2-ones and oxindoles.
Scheme 1.
Scheme 1.
Previous Reports and This Work
Scheme 2.
Scheme 2.
Hypothesis
Scheme 3.
Scheme 3.
Oxidative Coupling of Aryl Malononitriles With Phenols, Anilines, and Heteroarenesa aReaction conditions: 1 (0.1 mmol), 2 (0.25 mmol), Cu(OTf)2 (0.01 mmol), K2S2O8 (0.2 mmol), acetonitrile (0.75 mL) at 60 °C or 100 °C.
Scheme 4.
Scheme 4.
Substrate Scope of 3-Arylbenzofuran-2-ones and 3-Aryloxindoles with Phenols, Anilines and Heteroarenesa aReaction conditions: 4 (0.1 mmol), 2 (0.25 mmol), Cu(OTf)2 (0.01 mmol), K2S2O8 (0.2 mmol), acetonitrile (0.75 mL) at 60 °C. a100 °C.
Scheme 5.
Scheme 5.
Reactions with Dimer and Methanol
Scheme 6.
Scheme 6.
Proposed Mechanism
See this image and copyright information in PMC

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