Late-stage electron-catalyzed perfluoroalkylation of coumarin derivatives—Thermal fluoroalkyl radical production from sodium perfluoroalkyl sulfinate salts

Torviso, M. Rosario; Mansilla, Daniela; Garcia, Selva; Lantaño, Beatríz; Barata‐Vallejo, Sebastián; Postigo, Al

doi:10.1016/j.jfluchem.2017.03.005

Cited by 11 publications

(4 citation statements)

References 31 publications

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“…On the other hand, the strong chromophoric character of organic dyes,, being inexpensive, nontoxic, readily available and the fact that can be easily separated/extracted from the reaction mixtures render them excellent environmentally superior alternatives to metal complexes. To that effect, organic dyes such as Rose Bengal, Eosin Y, Red Nile, anthraquinone‐2‐carboxylic, anthraquinone‐2‐sulfonic acids and others have successfully been employed in the production of carbon‐centered radicals triggered by visible light irradiation. Moreover, photocatalysts absorbing in the red region of the electromagnetic spectrum have allowed even lower energy irradiation sources to be used capable of effecting reductive quenching cycles (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Electron Donor‐Acceptor Complexes in Perfluoroalkylation Reactions

Postigo

2018

Eur J Org Chem

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136

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Electron‐donor‐acceptor complexes (EDA) can be established through halogen‐bonding interactions between the N lone electron pair from organic bases (or N‐/O‐centered anions) and perfluoroalkyl iodides RF–I. These EDA complexes can be activated thermally or photochemically, and will be shown to be responsible for new C–RF bond formation reactions, bypassing the use of visible‐light photocatalysts (either organic or organometallic) or harsh reaction conditions, thus simplifying reaction protocols, work‐up and analysis. Through this strategy, diverse reaction types can be realized, such as atom transfer radical additions, homolytic aromatic substitutions, and multicomponent reactions.

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Section: Introductionmentioning

confidence: 99%

Electron Donor‐Acceptor Complexes in Perfluoroalkylation Reactions

Postigo

2018

Eur J Org Chem

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136

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“…The visible-light photoreaction (RB-photocatalyzed) of 4-formylpyridine-N-oxide 47 under the reaction conditions of Table 2 does not afford any substitution product. Use of other sacrificial donors ( potassium oxalate 26 ) or photocatalysts (anthraquinone-2-sulfonic acid 26 or Eosin Y) affords no substitution, probably due to the deactivation of the heteroaromatic nucleus and poor electron-availability.…”

Section: Resultsmentioning

confidence: 99%

Organic dye-photocatalyzed fluoroalkylation of heteroarene-N-oxide derivatives

2018

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The first direct CHet-H perfluoroalkylation reaction of heteroaromatic-N-oxides has been achieved through a visible light-photocatalyzed reaction in the presence of commercially available perfluoroalkyl iodides RF-I and base in DMF as solvent and Rose Bengal as organic photocatalyst. The reactions proceed in the absence of transition metals and can be scaled up. Through an acid-catalyzed transformation of the perfluoroalkylated-N-oxides thus obtained, the first direct syntheses of 2-(perfluoroalkyl)benzo[f][1,3]oxazepines are achieved. De-oxygenation of the resulting perfluoroalkylated heteroaromatic-N-oxides leads to high yielding and regioselective radical perfluoroalkylation protocols of heteroaromatic compounds. To the best of our knowledge, this is the first report on a direct method for perfluoroalkylation of pyridine-, quinoline-, and diazine-N-oxide derivatives.

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“…16 For example, in 2017 Postigo's group reported a stoichiometric Cu( ii )-mediated oxidative process for the synthesis of 3-perfluoroalkyl-substituted coumarins (Scheme 1a). 17 Regrettably, the work only showed a very limited substrate scope. When 4-anilinocoumarin was employed as a substrate under identical conditions, only a trace amount of the desired perfluoroalkylation product was detected (see ESI†), which is probably due to the coordination between the excess amount of Cu( ii ) salts and the sensitive amino groups thus poisoning the reaction.…”

Section: Introductionmentioning

confidence: 98%