Dataset Information

Visible Light Promoted, Catalyst-Free Radical Carbohydroxylation and Carboetherification under Mild Biomimetic Conditions.

ABSTRACT: Metal and catalyst-free carbohydroxylations and carboetherifications at room temperature have been achieved by a combination of beneficial factors including high aryl diazonium concentration and visible light irradiation. The acceleration of the reaction by visible light irradiation is particularly remarkable against the background that neither the aryldiazonium salt nor the alkene show absorptions in the respective range of wavelength. These observations point to weak charge transfer interactions between diazonium salt and alkene, which are nevertheless able to considerably influence the reaction course. As highly promising perspective, many more aryldiazonium-based radical arylations might benefit from simple light irradiation without requiring a photocatalyst or particular additive.

SUBMITTER: Altmann LM

PROVIDER: S-EPMC7898656 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Visible Light Promoted, Catalyst-Free Radical Carbohydroxylation and Carboetherification under Mild Biomimetic Conditions.

Altmann Lisa-Marie LM Zantop Viviane V Wenisch Pia P Diesendorf Nina N Heinrich Markus R MR

Chemistry (Weinheim an der Bergstrasse, Germany) 20201229 7

Metal and catalyst-free carbohydroxylations and carboetherifications at room temperature have been achieved by a combination of beneficial factors including high aryl diazonium concentration and visible light irradiation. The acceleration of the reaction by visible light irradiation is particularly remarkable against the background that neither the aryldiazonium salt nor the alkene show absorptions in the respective range of wavelength. These observations point to weak charge transfer interactio ...[more]

PMID: 33006177

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Project description:Harnessing visible light as the driving force for chemical transformations generally offers a more environmentally friendly alternative compared with classical synthetic methodology. The transition metal-based photocatalysts commonly employed in photoredox catalysis absorb efficiently in the visible spectrum, unlike most organic substrates, allowing for orthogonal excitation. The subsequent excited states are both more reducing and more oxidizing than the ground state catalyst and are competitive with some of the more powerful single-electron oxidants or reductants available to organic chemists yet are simply accessed via irradiation. The benefits of this strategy have proven particularly useful in radical chemistry, a field that traditionally employs rather toxic and hazardous reagents to generate the desired intermediates. In this Account, we discuss our efforts to leverage visible light photoredox catalysis in radical-based bond-forming and bond-cleaving events for which few, if any, environmentally benign alternatives exist. Mechanistic investigations have driven our contributions in this field, for both facilitating desired transformations and offering new, unexpected opportunities. In fact, our total synthesis of (+)-gliocladin C was only possible upon elucidating the propensity for various trialkylamine additives to elicit a dual behavior as both a reductive quencher and a H-atom donor. Importantly, while natural product synthesis was central to our initial motivations to explore these photochemical processes, we have since demonstrated applicability within other subfields of chemistry, and our evaluation of flow technologies demonstrates the potential to translate these results from the bench to pilot scale. Our forays into photoredox catalysis began with fundamental methodology, providing a tin-free reductive dehalogenation that exchanged the gamut of hazardous reagents previously employed for such a transformation for visible light-mediated, ambient temperature conditions. Evolving from this work, a new avenue toward atom transfer radical addition (ATRA) chemistry was developed, enabling dual functionalization of both double and triple bonds. Importantly, we have also expanded our portfolio to target clinically relevant scaffolds. Photoredox catalysis proved effective in generating high value fluorinated alkyl radicals through the use of abundantly available starting materials, providing access to libraries of trifluoromethylated (hetero)arenes as well as intriguing gem-difluoro benzyl motifs via a novel photochemical radical Smiles rearrangement. Finally, we discuss a photochemical strategy toward sustainable lignin processing through selective C-O bond cleavage methodology. The collection of these efforts is meant to highlight the potential for visible light-mediated radical chemistry to impact a variety of industrial sectors.

Dataset Information

Visible Light Promoted, Catalyst-Free Radical Carbohydroxylation and Carboetherification under Mild Biomimetic Conditions.

Publications

Visible Light Promoted, Catalyst-Free Radical Carbohydroxylation and Carboetherification under Mild Biomimetic Conditions.

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