Electrochemistry of natural products. IV. Electrochemical and chemical oxidative dimerization of 1,2-dimethyl-7-hydroxy-6-methoxy-1,2,3,4-tetrahydroisoquinoline

Bobbitt, James M.; Noguchi, I.; Yagi, H.; Weisgraber, Karl H.

doi:10.1021/jo00867a021

Cited by 26 publications

(9 citation statements)

References 2 publications

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“…This transformation was carried out under conditions devised by Bobbit for a related set of electron-rich arene substrates. 486 Notably, constant potential electrolysis of substrates in a divided electrochemical cell equipped with graphite anode, Pt cathode, Et 4 N + ClO 4 – supporting electrolyte, and NaOMe as a stoichiometric additive in MeCN/H 2 O (19:1) led to the synthesis of Pummerer ketones from p -cresol ( 180.1 ), 4-ethylphenol ( 180.2 ), and 3,4- and 2,4-dimethylphenol ( 180.3 , 180.4 ) (four examples, 20–37% yields).…”

Section: O -Centered Radical Generation From O–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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We present here a review of the photochemical and electrochemical applications of multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms in which both an electron and a proton are exchanged together, often in a concerted elementary step. As such, MS-PCET can function as a non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from a wide variety of common organic functional groups. We present an introduction to MS-PCET and a practitioner’s guide to reaction design, with an emphasis on the unique energetic and selectivity features that are characteristic of this reaction class. We then present chapters on oxidative N–H, O–H, S–H, and C–H bond homolysis methods, for the generation of the corresponding neutral radical species. Then, chapters for reductive PCET activations involving carbonyl, imine, other X=Y π-systems, and heteroarenes, where neutral ketyl, α-amino, and heteroarene-derived radicals can be generated. Finally, we present chapters on the applications of MS-PCET in asymmetric catalysis and in materials and device applications. Within each chapter, we subdivide by the functional group undergoing homolysis, and thereafter by the type of transformation being promoted. Methods published prior to the end of December 2020 are presented.

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Section: O -Centered Radical Generation From O–h Bonds Through Photochemical and Electrochemical Pcet Processesmentioning

confidence: 99%

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

et al. 2021

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“…Phenols (usually in alkaline media) and aryl alkyl ethers were also studied extensively. In the case of phenols, carbon–oxygen coupling often competes with the desired carbon–carbon coupling 94. In contrast, alkyl aryl ethers can often be coupled very selectively, and the yields of the products are typically very high (85 % for 1,2,4‐trimethoxybenzene,95 95 % for 9‐methoxyanthracene) 96…”

Section: Oxidative Aromatic Couplingmentioning

confidence: 99%

Comparison of Oxidative Aromatic Coupling and the Scholl Reaction

et al. 2013

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Does the dehydrogenative coupling of aromatic compounds mediated by AlCl3 at high temperatures and also by FeCl3, MoCl5, PIFA, or K3[Fe(CN)6] at room temperature proceed by the same mechanism in all cases? With the growing importance of the synthesis of aromatic compounds by double C-H activation to give various biaryl structures, this question becomes pressing. Since some of these reactions proceed only in the presence of non-oxidizing Lewis acids and some only in the presence of certain oxidants, the authors venture the hypothesis that, depending on the electronic structure of the substrates and the nature of the "catalyst", two different mechanisms can operate. One involves the intermediacy of a radical cation and the other the formation of a sigma complex between the acid and the substrate. The goal of this Review is to encourage further mechanistic studies hopefully leading to an in-depth understanding of this phenomenon.

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“…Auch Phenole (gewöhnlich in alkalischen Medien) und Arylalkylether wurden eingehend untersucht. Im Fall von Phenolen konkurriert die Kohlenstoff‐Sauerstoff‐Kupplung oft mit der gewünschten Kohlenstoff‐Kohlenstoff‐Kupplung 94. Dagegen können Alkylarylether oft sehr selektiv gekuppelt werden, und die Ausbeuten der Produkte sind typischerweise sehr hoch (85 % für 1,2,4‐Trimethoxybenzol,95 95 % für 9‐Methoxyanthracen) 96…”

Section: Oxidative Aromatische Kupplungunclassified

Oxidative aromatische Kupplung und Scholl‐Reaktion im Vergleich

et al. 2013

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Läuft die durch AlCl3 bei hoher Temperatur und auch durch FeCl3, MoCl5, PIFA oder K3[Fe(CN)6] bei Raumtemperatur vermittelte, dehydrierende Kupplung aromatischer Verbindungen in allen Fällen nach dem gleichen Mechanismus ab? Durch die wachsende Bedeutung der Synthese aromatischer Verbindungen durch doppelte C‐H‐Aktivierung, die zu unterschiedlichen Biarylen führt, wird diese Frage dringlicher. Da einige dieser Reaktionen nur in Gegenwart nichtoxidierender Lewis‐Säuren ablaufen und andere nur in Gegenwart bestimmter Oxidationsmittel, wagen die Autoren die Hypothese, dass abhängig von der elektronischen Struktur der Substrate und der Natur des “Katalysators” zwei unterschiedliche Mechanismen ablaufen können. Der eine verläuft über ein Radikalkation als Intermediat, der andere über die Bildung eines Sigma‐Komplexes zwischen Säure und Substrat. Das Ziel dieses Aufsatzes ist es, weitere mechanistische Studien anzuregen, die zu einem eingehenden Verständnis dieses Phänomens führen sollen.

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Electrochemistry of natural products. IV. Electrochemical and chemical oxidative dimerization of 1,2-dimethyl-7-hydroxy-6-methoxy-1,2,3,4-tetrahydroisoquinoline

Abstract: 41) NB. The concentrations of the substrate and of bromine in this mixture were thus half that In the Initial solutions. (42) Sadtler32 uv spectrum no. 16495. (43) A

Cited by 26 publications

References 2 publications

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Comparison of Oxidative Aromatic Coupling and the Scholl Reaction

Oxidative aromatische Kupplung und Scholl‐Reaktion im Vergleich

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