Emodin as a novel organic photocatalyst for selective oxidation of sulfides under mild conditions

Zhang, Yan; Lou, Jiangli; Yuan, Zhenbo; Rao, Yijian

doi:10.1039/d0ra02702b

Cited by 16 publications

(14 citation statements)

References 57 publications

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“…The following year, the same group, observing the structural similarity of the natural product Emodin (20) with Cercosporin (19) due to the quinone skeleton, envisaged its photocatalytic activity (Scheme 10, C). [28] Their hypothesis proved to be correct as Emodin displayed a similar efficacy for the oxidation as 19.…”

Section: Dyesmentioning

confidence: 94%

“…Different kind of natural products with strong resemblance to perylene structure were also reported as potential photocatalysts (Scheme 10, C). [27,28] Cercosporin ( 19) is a natural product, derived from plant pathogenic fungus species Cercospora and belongs to the class of perylene quinonoid pigments. Zhang and Rao employed 19 as an efficient photocatalyst for aerobic oxidation reactions in general, including sulfide oxidations.…”

Section: Dyesmentioning

confidence: 99%

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Aerobic Photocatalysis: Oxidation of Sulfides to Sulfoxides

2022

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Sulfoxides constitute one of the most important functional groups in organic chemistry found in numerous pharmaceuticals and natural products. Sulfoxides are usually obtained from the oxidation of the corresponding sulfides. Among various oxidants, oxygen or air are considered the greenest and most sustainable reagent. Photochemistry and photocatalysis is increasingly applied in new, as well as traditional, yet demanding, reaction, like the aerobic oxidation of sulfides to sulfoxides, since photocatalysis has provided the means to access them in mild and effective ways. In this review, we will summarize the photochemical protocols that have been developed for the oxidation of sulfides to sulfoxides, employing air or oxygen as the oxidant. The aim of this review is to present: i) a historical overview, ii) the key mechanistic studies and proposed mechanisms and iii) categorize the different catalytic systems in literature.Scheme 2. Traditional sulfide oxidation methods. Scheme 3. Sulfide oxidation methods utilizing oxygen as the oxidant.

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Section: Dyesmentioning

confidence: 94%

Section: Dyesmentioning

confidence: 99%

Aerobic Photocatalysis: Oxidation of Sulfides to Sulfoxides

2022

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“…Emodin (Scheme 5), a naturally occurring active component of several plants such as Rheum palmatum used in traditional Chinese medicine, has also been identified as having potential antiviral activity against coronaviruses such as SARS‐CoV‐2 [45,46] . Zhang, Rao and colleagues [47] have very recently employed Emodin for the visible light‐photocatalyzed oxidation of sulfides to sulfoxides in methanol as solvent in the presence of air, irradiating with a 5 W blue LED, The scope of the transformation is illustrated in Scheme 5.…”

Section: Oxidationsmentioning

confidence: 99%

“…The authors [47] investigated the reaction mechanism through probe experiments, employing radical scavengers such as TEMPO and singlet oxygen scavengers, such as DABCO. In both cases, they found a notorious decrease in sulfoxide product yield.…”

Section: Oxidationsmentioning

confidence: 99%

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Bioinspired Photocatalyzed Organic Synthetic Transformations. The Use of Natural Pigments and Vitamins in Photocatalysis

2022

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Due to the necessity for more environmentally benign processes in synthetic organic chemistry, and in particular in photocatalysis, a recourse to photocatalysts that are also found in nature and mimic natural processes to accomplish organic transformations is very appealing. Synthetic useful reactions such as oxidations, reductions, carbon-oxygen, carbon-carbon and carbon-sulfur bond formation reactions, and E-to-Z geo-metrical isomerization reactions photocatalyzed by biological natural pigments, vitamins, cofactors, and compounds with antiviral activity will be discussed in this account. Interestingly, due to the remarkable redox properties and triplet energies of some of these catalysts that are found in nature, both electron transfer (ET)-and energy transfer (EnT)-driven photocatalytic processes can be accomplished.

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3H‐Phenothiazin‐3‐one: A Photocatalyst for the Aerobic Photochemical Oxidation of Sulfides to Sulfoxides

Spyropoulou,

Skolia,

Flesariu

et al. 2023

Adv Synth Catal

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In this study, 3H‐phenothiazin‐3‐one is identified as a photocatalyst for the photochemical oxidation of sulfides to sulfoxides. This photocatalytic method uses a low catalyst loading (0.05 mol%), molecular oxygen as the sole oxidant, and a blue LED lamp as the irradiation source. It can be applied to the oxidation of both alkyl‐aryl and alkyl‐alkyl sulfides. Moreover, the method is also applicable in the synthesis of the known pharmaceutically active compounds Modafinil and Sulforaphane.

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Emodin as a novel organic photocatalyst for selective oxidation of sulfides under mild conditions

Abstract: Naturally-occurring Emodin was successfully employed in the selective oxidation of sulfides promoted by visible-light as a novel organic photocatalyst for the first time.

Cited by 16 publications

References 57 publications

Aerobic Photocatalysis: Oxidation of Sulfides to Sulfoxides

Aerobic Photocatalysis: Oxidation of Sulfides to Sulfoxides

Bioinspired Photocatalyzed Organic Synthetic Transformations. The Use of Natural Pigments and Vitamins in Photocatalysis

3H‐Phenothiazin‐3‐one: A Photocatalyst for the Aerobic Photochemical Oxidation of Sulfides to Sulfoxides

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