Unexpected Dual Role of Titanium Dioxide in the Visible Light Heterogeneous Catalyzed C–H Arylation of Heteroarenes

Zoller, Jochen; Fabry, David C.; Rueping, Magnus

doi:10.1021/acscatal.5b00668

Cited by 122 publications

(87 citation statements)

References 87 publications

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“…Such photocatalyzed reactions can be conducted with a number of aryl radical precursors including diazonium and iodonium salts, diazoanhydrides, carboxylic acids, azo sulfones, and iodo‐, bromo‐, and chloroarenes . Typically employed photocatalysts are complexes of ruthenium or iridium, eosin Y, titanium dioxide,, or strong electron donors, and double excitation of perylene bisimide recently allowed the conversion of aryl chlorides …”

Section: Methodsmentioning

confidence: 99%

Visible‐Light‐Induced, Catalyst‐Free Radical Arylations of Arenes and Heteroarenes with Aryldiazonium Salts

Fürst

Gans

Bock

et al. 2017

Chemistry A European J

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In the absence of a photocatalyst and other additives, the radical arylation of diverse arenes and heteroarenes has been achieved with aryldiazonium salts under visible-light irradiation from a blue light-emitting diode (LED). Although the course of some reactions can be rationalized by the formation of strongly light-absorbing charge-transfer (CT) complexes between the diazonium ion and the aromatic substrate, several further examples indicated that the simple presence of an aromatic substrate, showing only weak interactions to the diazonium ion, is fully sufficient to enable product formation.

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Section: Methodsmentioning

confidence: 99%

Visible‐Light‐Induced, Catalyst‐Free Radical Arylations of Arenes and Heteroarenes with Aryldiazonium Salts

Fürst

Gans

Bock

et al. 2017

Chemistry A European J

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“…[6e] TheU V/Vis absorption spectrum of (4-CF 3 C 6 H 4 ) 3 PAuCl showed av ery weak absorption band at 450 nm (e = 17), which excludes the possibility of (4-CF 3 C 6 H 4 ) 3 PAuCl being aphotosensitizer itself.Alight on/off experiment showed that the transformation required continuous irradiation with blue LEDs (see the Supporting Information), excluding the possibility that an efficient radical-chain propagation mechanism is operating. [11] However,d espite the fact that these species might also be formed in the gold-catalyzed process,their role in the reaction remains unclear. We assume that the reaction is initiated by goldinduced single electron transfer (SET) to the aryl diazonium salt, generating an aryl diazo radical and gold(II) species A.…”

Section: Angewandte Chemiementioning

confidence: 99%

Photosensitizer‐Free Visible‐Light‐Mediated Gold‐Catalyzed 1,2‐Difunctionalization of Alkynes

et al. 2016

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Under visible-light irradiation, the gold-catalyzed intermolecular difunctionalization of alkynes with aryl diazonium salts in methanol affords a variety of α-aryl ketones in moderate to good yields. In contrast to previous reports on gold-catalyzed reactions that involve redox cycles, no external oxidants or photosensitizers are required. The reaction proceeds smoothly under mild reaction conditions and shows broad functional-group tolerance. Further applications of this method demonstrate the general applicability of the arylation of a vinyl gold intermediate instead of the commonly used protodemetalation step. This step provides facile access to functionalized products in one-pot processes. With a P,N-bidentate ligand, a stable aryl gold(III) species was obtained, which constitutes the first direct experimental evidence for the commonly postulated direct oxidative addition of an aryl diazonium salt to a pyridine phosphine gold(I) complex.

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“…Rueping et al used TiO 2 to mediate the intermolecular coupling between arenediazonium salts and heteroaromatics (Scheme ) . They found that the reaction proceeds through formation of TiO 2 ‐azoethers, which undergoes excitation upon the visible light irradiation.…”

Section: C–c Bond: Sp2‐sp2 Disconnectionmentioning

confidence: 99%

A Retrosynthetic Approach for Photocatalysis

et al. 2020

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Visible‐light‐mediated chemical reactions have become very popular within the last 15 years. Many excellent reviews have summarized reaction principles and recent results in photochemistry and photocatalysis. However, despite their popularity photochemistry and photoredox catalysis are not regular parts of the bachelor and master curriculum of chemistry education. As a consequence, most chemists will use in synthesis planning classic retrosynthetic disconnections and only rarely consider photocatalytic steps. The aim of this article is to be a useful tool for synthetic chemists, that are interested in the synthetic aspects of photocatalysis and looking for a specific retrosynthetic disconnection. Not only are informative schemes provided but also are the availability of the catalysts and reagents as well as the functional group tolerance of the respective method briefly discussed.

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Unexpected Dual Role of Titanium Dioxide in the Visible Light Heterogeneous Catalyzed C–H Arylation of Heteroarenes

Cited by 122 publications

References 87 publications

Visible‐Light‐Induced, Catalyst‐Free Radical Arylations of Arenes and Heteroarenes with Aryldiazonium Salts

Visible‐Light‐Induced, Catalyst‐Free Radical Arylations of Arenes and Heteroarenes with Aryldiazonium Salts

Photosensitizer‐Free Visible‐Light‐Mediated Gold‐Catalyzed 1,2‐Difunctionalization of Alkynes

A Retrosynthetic Approach for Photocatalysis

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