Electrochemical benzylic oxidation of C–H bonds

Marko, Jason A.; Durgham, Anthony; Bretz, Stacey Lowery; Liu, Wei

doi:10.1039/c8cc08768g

Cited by 64 publications

(44 citation statements)

References 57 publications

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“…Recently, Liu and collaborators reported the use of tert-butyl hydroperoxide for the direct activation of benzylic CÀ H bonds via HAT by the tert-butyl peroxyl radical formed through anodic oxidation (Scheme 31). [73] The reaction conditions were effective for the oxidation of a wide variety of substrates, spanning from variously substituted tolyl analogues to heteroaryl derivatives, providing the corresponding ketones in modest-to-excellent yields.…”

Section: C(sp 3 )à O Bond Formationmentioning

confidence: 99%

Photochemical and Electrochemical Strategies towards Benzylic C−H Functionalization: A Recent Update

et al. 2021

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Transition metal-catalysed processes have been widely used for the functionalization of inert CÀ H bonds. Strategies for the functionalization of the benzylic CÀ H position having a relatively weak CÀ H bond (bond dissociation energy~80-90 kcal/mol) differ from the inert aliphatic and aromatic CÀ H positions with stronger CÀ H bonds. The recent advances in the direct activation of the benzylic position through the generation of C(sp 3) radicals have demonstrated the potential of electrochemistry and photochemistry as a means for constructing new chemical bonds. This review will cover the recent progress of benzylic CÀ H functionalization through organic radical strategies employing photochemistry and electrochemistry as sustainable tools. In addition, the mechanistic details of the typical reactions have been included which, in turn, will help the researchers to look at this promising area from a different perspective towards new discoveries and often hidden opportunities. 2.1. C(sp 3)À C Bond Formation 2.2. C(sp 2)À O and C(sp 3)À O Bond Formation 2.3. C(sp 3)À N Bond Formation 2.4. C(sp 3)À S Bond Formation 2.5. C(sp 3)À Halogen Bond Formation 3. Electrochemical Benzylic C(sp 3)À H Functionalization 3.1. C(sp 3)À C Bond Formation 3.2. C(sp 3)À O Bond Formation 3.3. C(sp 3)À N Bond Formation 3.4. C(sp 3)À P Bond Formation 3.5. C(sp 3)À Halogen Bond Formation 4. Benzylic C(sp 3)À H Functionalization via Synthetic Photoelectrochemistry 5. Conclusions and Outlook

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Section: C(sp 3 )à O Bond Formationmentioning

confidence: 99%

Photochemical and Electrochemical Strategies towards Benzylic C−H Functionalization: A Recent Update

et al. 2021

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“…4 Current methods provide direct access to the corresponding phenones. 5 While phenones can often be reduced to alcohols, 6 the conversion of benzylic C–H bonds to benzylic alcohols without the need for a reduction step is currently an unsolved problem and provides a complementary approach to prior art. Herein, we present the selective monooxygenation of primary and secondary benzylic C–H bonds: the problem of chemoselective reduction of phenones to alcohols in the presence of other carbonyl functionality is eliminated, and alkenes as well as alkynes, typically sensitive to oxidative reaction conditions, 5a,7 are tolerated, as are basic amines.…”

mentioning

confidence: 99%

Synthesis of Benzylic Alcohols by C–H Oxidation

2019

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Selective methylene C–H oxidation for the synthesis of alcohols with a broad scope and functional group tolerance is challenging due to the high proclivity for further oxidation of alcohols to ketones. Here, we report the selective synthesis of benzylic alcohols employing bis(methanesulfonyl) peroxide as an oxidant. We attempt to provide a rationale for the selectivity for monooxygenation, which is distinct from previous work; a proton-coupled electron transfer mechanism (PCET) may account for the difference in reactivity. We envision that our method will be useful for applications in the discovery of drugs and agrochemicals.

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“…The electrogenerated stable allylic radical ( 182 ) reacts with t‐ BuOOH, after elimination of t‐ BuOH, the desired conjugated carbonyl product ( 181 b ) is obtained. A similar strategy for benzylic C−H oxidation was developed using t ‐butyl hydroperoxide as mediator and oxygen source [129] …”

Section: C‐centered Radicalsmentioning

confidence: 99%

Electrochemical Generation and Use in Organic Synthesis of C‐, O‐, and N‐Centered Radicals

Chicas-Baños

Frontana‐Uribe

2021

The Chemical Record

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During the last decade several research groups have been developing electrochemical procedures to access highly functionalized organic molecules. Among the most exciting advances, the possibility of using free radical chemistry has attracted the attention of the most important synthetic groups. Nowadays, electrochemical strategies based on these species with a synthetic purpose are published continuously in scientific journals, increasing the alternatives for the synthetic organic chemistry laboratories. Free radicals can be obtained in organic electrochemical reactions; thus, this review reassembles the last decade's (2010–2020) efforts of the electrosynthetic community to generate and take advantage of the C‐, O‐, and N‐centered radicals’ reactivity. The electrochemical reactions that occur, as well as the proposed mechanism, are discussed, trying to give clear information about the used conditions and reactivity of these reactive intermediate species.

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Electrochemical benzylic oxidation of C–H bonds

Abstract: An electrochemical benzylic C–H oxidation reaction that is mediated by tert-butyl peroxyl radical is reported.

Cited by 64 publications

References 57 publications

Photochemical and Electrochemical Strategies towards Benzylic C−H Functionalization: A Recent Update

Photochemical and Electrochemical Strategies towards Benzylic C−H Functionalization: A Recent Update

Synthesis of Benzylic Alcohols by C–H Oxidation

Electrochemical Generation and Use in Organic Synthesis of C‐, O‐, and N‐Centered Radicals

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