Thermally Induced Carbohydroxylation of Styrenes with Aryldiazonium Salts

Kindt, M. Sc. Stephanie; Wicht, Karina; Heinrich, Markus R.

doi:10.1002/anie.201601656

Cited by 69 publications

(66 citation statements)

References 74 publications

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“…[47] Likewise, DG z 0 was determined to be 0.33 eV for acyl radicals, [48] 0.32 eV for the cyanomethyl radical, [34] and as low as 0.11 eV for the delocalized benzyl radicals. [44] These numbers are a reflection of the fact that both the solvent and inner reorganization energies are comparatively much larger for the alkyl radicals, since the reduction to the corresponding alkyl anions results in both a strong localization of the negative charge and a change in hybridization from sp 2 to sp 3…”

Section: Collects the Computed E Omentioning

confidence: 99%

“…, plays a pivotal role in many functional transformation reactions in organic cemistry ,. A recent example pertains to the radical carboxyhydroxylation of styrene with aryldiazonium salts . The hydrogen abstraction reaction constitutes perhaps the simplest transformation at all, in that Ar .…”

Section: Introductionmentioning

confidence: 99%

“…[1,2] A recent example pertains to the radical carboxyhydroxylation of styrene with aryldiazonium salts. [3] The hydrogen abstraction reaction constitutes perhaps the simplest transformation at all, in that Ar * is converted to the corresponding arene. [4] While the high reactivity of free radicals, in general, can be considered to be a great advantage from a synthetic point of view, e. g., in polymerization reactions, [5] the limitations induced by the presence of side reactions may, unfortunately, overshadow the advantages.…”

Section: Introductionmentioning

confidence: 99%

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On the Kinetic and Thermodynamic Properties of Aryl Radicals Using Electrochemical and Theoretical Approaches

et al. 2017

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In this work, sampled‐current voltammetry performed on a series of aryldiazonium, diaryliodonium, and triarylsulfonium salts allows the determination of the reduction potential of aryl radicals in acetonitrile. Specifically, this is accomplished by measuring the number of electrons consumed in the reduction process as a function of the applied potential. For the phenyl, 4‐bromophenyl, and 4‐nitrophenyl radicals, the reduction potential is found to be −0.91±0.06, −0.90±0.10, and −0.98±0.06 V vs. SCE, respectively. Furthermore, from measurements on an extended series of substituted compounds, it is concluded that the substituent effect on the reduction potential is small, which can be explained by the σ nature of the aryl radical as evidenced from theoretical calculations. At the same time this yields a mean value for the reduction potential of the aryl radical of −0.87 V±0.03 V vs. SCE. Determination of the intrinsic barrier and the standard potential from the data obtained are more uncertain since it is unknown to which extent the competing reference reaction, the electrochemical grafting reaction, is affected by the applied potential. From calculations using density functional theory, the intrinsic barrier for the reduction of the phenyl radical is determined to be 0.32 eV.

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Section: Collects the Computed E Omentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Kinetic and Thermodynamic Properties of Aryl Radicals Using Electrochemical and Theoretical Approaches

et al. 2017

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“…The proposed scenario involving the intermediacy of the iminium species is supported by the isolation of 18 c in the presence of methanol. A radical chain mechanism has not been ruled out …”

Section: Figurementioning

confidence: 99%

Catalytic Arylhydroxylation of Dehydroalanine in Continuous Flow for Simple Access to Unnatural Amino Acids

Khan

Zhao

Scully

et al. 2018

Chemistry A European J

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This report discloses the first example of catalytic arylhydroxylation of dehydroalanine with aryldiazonium salts. Aryldiazonium salts, which are generated from aniline precursors under partially aqueous conditions in continuous flow, efficiently reacted with dehydroalanine in the presence of 10-15 mol % ferrocene to furnish α-hydroxyarylalanine derivatives (up to 82 % yield). The reactions proceeded with regioselectivity, broad functional group tolerance, and without polymerization of the dehydroalanine. Furthermore, the products were used to access α-unnatural amino acids, important targets with application in drug development.

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“…Radical intermediate B can undergo C-N homolytic bond cleavage that leads to nitrogen extrusion and the final aryl radical. 14 We currently believe that the interplay between the nucleophile and diazonium salt is critical in the base-mediated Au-redox system, as we have previously disclosed a Lewis-base assisted diazonium activation condition to achieve several cross coupling reactions. 15 More specifically, C-C, C-Br, C-S and C-P bonds could be efficiently made through intermolecular coupling.…”

Section: Introductionmentioning

confidence: 99%

Gold Redox Catalysis through Base‐Initiated Diazonium Decomposition toward Alkene, Alkyne, and Allene Activation

Dong

Peng

Motika

et al. 2017

Chemistry A European J

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The discovery of photo-assisted diazonium activation toward gold(I) oxidation greatly extended the scope of gold redox catalysis by avoiding the use of a strong oxidant. Some practical issues that limit the application of this new type of chemistry are the relative low efficiency (long reaction time and low conversion) and the strict reaction condition control that is necessary (degassing and inert reaction environment). Herein, an alternative photo-free condition has been developed through Lewis base induced diazonium activation. With this method, an unreactive Au(I) catalyst was used in combination with Na2CO3 and diazonium salts to produce a Au(III) intermediate. The efficient activation of various substrates, including alkyne, alkene and allene was achieved, followed by rapid Au(III) reductive elimination, which yielded the C-C coupling products with good to excellent yields. Relative to the previously reported photo-activation method, our approach offered greater efficiency and versatility through faster reaction rates and broader reaction scope. Challenging substrates such as electron rich/neutral allenes, which could not be activated under the photo-initiation conditions (<5% yield), could be activated to subsequently yield the desired coupling products in good to excellent yield.

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Thermally Induced Carbohydroxylation of Styrenes with Aryldiazonium Salts

Cited by 69 publications

References 74 publications

On the Kinetic and Thermodynamic Properties of Aryl Radicals Using Electrochemical and Theoretical Approaches

On the Kinetic and Thermodynamic Properties of Aryl Radicals Using Electrochemical and Theoretical Approaches

Catalytic Arylhydroxylation of Dehydroalanine in Continuous Flow for Simple Access to Unnatural Amino Acids

Gold Redox Catalysis through Base‐Initiated Diazonium Decomposition toward Alkene, Alkyne, and Allene Activation

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