Selective Photooxidation Reactions using Water‐Soluble Anthraquinone Photocatalysts

Abstract

The aerobic organocatalytic oxidation of alcohols was achieved by using water‐soluble sodium anthraquinone sulfonate. Under visible‐light activation, this catalyst mediated the aerobic oxidation of alcohols to aldehydes and ketones. The photo‐oxyfunctionalization of alkanes was also possible under these conditions.

Visible‐Light‐Triggered Quantitative Oxidation of 9,10‐Dihydroanthracene to Anthraquinone by O2 under Mild Conditions

“…According to the present resultsand literature reports, [52][53][54][55][56] a mechanism of AQ-photocatalyzed DHA oxidation with O 2 is proposed as follows (Scheme 2): On the basis of the UV/Vis spectrum of high concentrations of AQ ( Figure S12 in the Supporting Information), AQ can absorb visiblel ight more efficiently than DHA to form its excited state AQ*. Then, this AQ*, which is probablym ore active than DHA*, directly abstracts one Ha tom on the 9o r1 0c arbon sites of DHA to yield its reduced species( K)a nd the above radical B.T hen, the radical B combines with oxygen to form its peroxy radical( C), and the latter is more likelytoabstract one Ha tom of the reduced species K to yield its hydroperoxide (D)a nd regenerate AQ (pho- ChemSusChem 2020, 13,1785 -1792 www.chemsuschem.org 2020 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim tocatalysis cycling pathway).…”

“…According to the present results and literature reports, a mechanism of AQ‐photocatalyzed DHA oxidation with O 2 is proposed as follows (Scheme ): On the basis of the UV/Vis spectrum of high concentrations of AQ (Figure S12 in the Supporting Information), AQ can absorb visible light more efficiently than DHA to form its excited state AQ*. Then, this AQ*, which is probably more active than DHA*, directly abstracts one H atom on the 9 or 10 carbon sites of DHA to yield its reduced species ( K ) and the above radical B .…”

Combining Photo‐Organo Redox‐ and Enzyme Catalysis Facilitates Asymmetric C‐H Bond Functionalization

“…SAS is a quinoid photo‐organo catalyst well‐known for the light‐driven oxidation of alcohols. It also catalyses oxyfunctionalisation of alkanes in benzylic and allylic positions with moderate efficiency, which are the by far more attractive reactions . Converting (non)activated C‐H‐bonds by SAS into aldehydes 12–15 or ketones 16–22 does not introduce chirality into the respective compounds.…”

Photocatalytic Oxidative Bromination of Electron‐Rich Arenes and Heteroarenes by Anthraquinone

“…The hypolipidemic agent gemfibrozil (24) and the anesthetic lidocaine (25) gave moderate yields due to a competing oxidation of the benzylic position to the corresponding aldehyde. [10] The reaction of the benzylic position could be exploited for toluene (30) (E Ox = 2.2 V vs SCE) [4a] if persulfate was used as sacrificial oxidant under inert atmosphere. In this case, it was possible to achieve exclusive bromination of the benzylic position in good yield (Scheme 1).…”