| Nowadays,with the global energy crisis and environmental pollution becoming more and more serious,visible light as a cheap and clean renewable energy has been widely concerned.In recent decades,with the development of ruthenium/iridium-based polypyridine complexes or organic dy es,and the development of semiconductor photocatalysts,visible light catalysis strategy has made great progress and has been applied to the synthesis of a variety of complex functional compounds.However,opportunities and challenges remained in the field of photocatalysis to realize efficient catalytic conversion based on cheap and abundant elementderived photocatalysts.In recent years,the photochemical activity of disulfide compounds is one of the hotspots of modern organic synthetic chemistry,has important significance in methodological research and industrial applications.From the view of green chemistry.the use of visible light as an energy source,molecular oxygen(O2)or ambient air as an oxidant,efficient and selective oxidation synthesis routes have received great attention.The research work of this paper is therefore extracted,and the following research results have been obtained:Firstly,a disulfide-mediated C-O?C-C and C-S bonds of 1,3-dicarbonyl compounds was developed.1)Under visible light catalysis,molecular oxygen is used as an oxidant to achieve?-hydroxylation reaction of ?-ketoester and ?-ketoamide.The reaction conditions are mild and the addition of metal salts,alkalis and reducing agents is avoided.2)The dioxetane intermediate formed by the oxidative cleavage of styrene under disulfide-mediated photocatalytic conditions is used as a methylation reagent,instead of the traditional toxic methylation reagent formaldehyde.The extension of the carbon chain of the dicarbonyl compound is realized.3)In addition,in the absence of visible light,disulfide is used as a sulfuration reagent with high atom economy.With CuI as the catalyst,the ?-sulfuration of ?-ketoester and ?-ketoamide is realized.Secondly,a disulfide-mediated selective oxidative coupling and oxidative deamination of benzylamine compounds to achieve construction of C-N bonds and cleavage of C-N bonds was developed.With benzothiazole disulfide as a catalyst,oxidative homo-coupling of benzylamine was disclosed for the construction of imine products with up to 87%.When the excitation light source is changed from blue light to purple light,benzylamine is oxidized and deaminated to generate benzaldehyde and its derivatives.The mild nature of the reaction conditions has been exemplified by the broad substrate scope facilely incorporated primary,secondary and tertiary amine with up to 83%yield.Besides,the corresponding amide and benzaldehyde derivatives were obtained when functional group fragment(such as the carbonyl group)introduced into the benzylamine substrate.Finally,a continuous flow strategy was applied to solve the problems of difficult amplification and low gas-liquid two-phase reaction efficiency faced by photocatalysis.The application of the continuous flow strategy realized the ?-hydroxylation and ?hydroxymethylation reactions of 1,3-dicarbonyl compounds,the residence time is shortened to 1/10 and 1/6 of the batch reaction time respectively,and the gram-scale amplification experiment is achieved with 84%and 71%yield.A continuous flow reaction device was built to compare with the commercial continuous flow photochemical reactor,which greatly shortened the reaction time,greatly improve the disulfide-mediated photocatalytic molecular oxygen oxidation reaction efficiency. |
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