One-pot epoxidation of alkenes using aerobic photoperoxidation of toluenes

Taguchi, M.; Nagasawa, Yoshitomo; Yamaguchi, Eiji; Tada, Norio; Miura, Tsuyoshi; Itoh, Akichika

doi:10.1016/j.tetlet.2015.12.027

Cited by 17 publications

(10 citation statements)

References 39 publications

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“…The same photocatalyst could be also applied to the one‐pot epoxidation of alkenes. In detail, a peroxybenzoic acid was obtained in situ from the corresponding methyl‐substituted aromatic compound under aerobic photooxidative conditions and used directly in the desired epoxidation process . The photooxygenation of alkanes can be promoted by excited benzoquinone derivatives through a direct HAT in the presence of molecular oxygen.…”

Section: Direct Hat Approachesmentioning

confidence: 99%

Hydrogen Atom Transfer (HAT): A Versatile Strategy for Substrate Activation in Photocatalyzed Organic Synthesis

2017

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The adoption of hydrogen atom transfer (HAT) in a photocatalytic approach, in which an excited catalyst is responsible for substrate activation, offers unique opportunities in organic synthesis, enabling the straightforward activation of R–H (R = C, Si, S) bonds in desired reagents. Either a direct strategy, based on the intrinsic reactivity of a limited number of photocatalysts in the excited state, or an indirect one, in which a photocatalytic cycle is used for the generation of a thermal hydrogen abstractor, can be exploited. This microreview summarizes the most recent advances (mainly from the last two years) in this rapidly developing area of research, collecting the selected examples according to the nature of the species promoting the HAT process. From the synthetic point of view, this area has led to the development of a plethora of strategies for C–C, C–Si, C–N, C–S, and C–halogen (particularly, fluorine) bond formation, as well as for oxidation reactions.

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Section: Direct Hat Approachesmentioning

confidence: 99%

Hydrogen Atom Transfer (HAT): A Versatile Strategy for Substrate Activation in Photocatalyzed Organic Synthesis

2017

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“…Another one-pot epoxidation protocol was developed by Itoh and coworkers, who reported the peroxidation of toluene (6) by 2-CO 2 H AQ as the photocatalyst, and the presumed peroxybenzoic acid intermediate (15) effected the epoxidation of alkenes under mild conditions (Scheme 16). [63] While it is more common to use aldehydes as precursors to peroxy acids in such reactions, toluene is much cheaper and more stable than aldehydes are. As a tradeoff, this procedure is relatively slow (20 h) due to the increased number of oxidation steps that occur from toluene.…”

Section: Photoperoxidation Of Toluene For In Situ Alkene Epoxidationmentioning

confidence: 99%

“…In the last decade, some researchers have begun to employ AQs in visible‐light induced, catalytic photooxidations obtaining products such as carboxylic acids, gem ‐diols, aromatic methyl esters, phenols, diacylamines, epoxides, and hydroxyalkyl esters. This activation involves either hydrogen‐atom or electron transfer …”

Section: Applications Of Aqs In Organic Synthesismentioning

confidence: 99%

Anthraquinones: Versatile Organic Photocatalysts

et al. 2020

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Anthraquinones (AQs) constitute the largest group of natural pigments, are commonly found in dyes, and are widely used in the textile industry due their photostability. They combine high absorptivity in the visible region with high excited‐state reduction potentials, making them effective acceptors of electrons and hydrogen atoms. AQs can be employed as organic catalysts in photooxidation reactions as well to produce reactive oxygen species (ROS). All these methods feature green chemistry aspects such as avoiding heavy metals, reducing waste, using inexpensive reagents, employing environmentally low‐impact solvents, and oxidizing with O2. This review covers the application of AQs in photoredox catalysis.

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“…Based on the Guo group's outstanding work, 9 literature precedents [59][60][61][62][63][64] and the cyclic voltammogram of AQ-PHEMA under irradiation (see Fig. S2 †), the following possible reaction Table 2 Photooxidation of thioethers into sulfoxides under Condition A a a All reactions were carried out using 1 (1 mmol) and AQ-PHEMA (1 mol%) in CH 3 OH (5 mL) irradiated by a purple LED light at rt under air atmosphere.…”

Section: Proposed Mechanismmentioning

confidence: 99%

“…This catalytic material could be recycled and reused aer catalyzing the photoreaction. With our continuing interest in the synthesis and application of PHEMA, 36 AQ-2-COOH [59][60][61] and PHEMA 36 were used to synthesize the designed polymeric photosensitizer AQ-PHEMA (Scheme 1) by immobilizing anthraquinone (AQ) onto PHEMA. In the next step, AQ-PHEMA (for synthesis and characterization of AQ-PHEMA, see ESI †) was tested as a photocatalyst in the visible light-induced photooxidation of thioethers under aerobic conditions.…”

Section: Introductionmentioning

confidence: 99%