Ru-Catalyzed aromatic C-H bond activation and functionalization have emerged as important topics because they have resulted in remarkable progress in organic synthesis. Both experimental and ...theoretical studies of their mechanisms are important for the design of new synthetic methodologies. In this review, a mechanistic view of the Ru-mediated C-H bond cleavage step is first given to reveal the C-H bond activation modes, including oxidative addition, metathesis and base-assisted deprotonation. In this process, directing groups play an important role in determining the reactivity of the C-H bond. The C-H bond activation generally leads to the formation of a Ru-C bond, which is further functionalized in the subsequent steps. The mechanisms of Ru-catalyzed arylation, alkylation, and alkenylation of arenes are summarized, and these transformations can be categorized into cross-coupling with electrophiles or oxidative coupling with nucleophiles. In addition, the mechanism of
ortho
-ruthenation-enabled remote C-H bond functionalization is also discussed.
This review summarized recent advances in the mechanistic study of Ru-catalyzed C-H bond functionalization from a theoretical perspective.
Background
Mount evidence from observational studies suggested that associations between sleep duration and the risks of mild cognitive impairment (MCI)/dementia or cognitive decline had been ...recognized.
Methods
To explore the precise and continuous effect of sleep duration on these risks, we conducted a dose–response meta-analysis to quantitatively assess it.
Results
Five prospective cohort studies and 4 cross-sectional studies were eligible for inclusion criteria, which involved 62937 individuals, and documented 2718 MCI/dementia cases and 5596 cognitive decline cases. The pooled RR per 1 h increases in sleep duration was 0.99 (95% CI 0.97–1.01,
I
2
= 62.40%,
P
= 0.02,
n
= 6) for cognitive decline risk, and 0.98 (95% CI 0.97–1.00,
I
2
= 0%,
P
= 0.42,
n
= 4) for MCI/dementia risk. Similar U-shaped non-linear relationship of sleep duration and the risks of MCI/dementia and cognitive decline was revealed, respectively (all
P
non-linearity
< 0.001), whose peaks are approximately 7 h.
Conclusion
In conclusion, 7 h sleep duration tends to acquire the least risk of MCI/dementia or cognitive decline; however, more well-designed randomized controlled trials are urgently needed to balance potential modifiers.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Water, as a green reaction medium, is safe, non-toxic, and rich in reserves on Earth, while visible light represents a renewable, clean, and abundant energy source. Organic transformations carried ...out under the irradiation of visible light in water are undoubtedly more attractive, and are in line with the concept of "green chemistry" to effectively minimize the environmental impact of chemical synthesis. This review focuses on the recent progress in visible-light-mediated organic transformations in water, and the related mechanisms are also discussed. Although great achievements have been made, they are just the tip of the iceberg and there is still great room for improvement. This review will facilitate the understanding of visible-light-mediated organic transformations in water and further stimulate the advancement of more novel relevant strategies.
Water is a green reaction medium, while visible light represents a renewable, clean, and abundant energy source. The recent advances in visible-light-mediated organic transformations in water are summarized.
A sustainable and cost‐effective protocol for direct aminomethylation of imidazo‐fused heterocycles by decarboxylative coupling reaction of N‐phenylglycines with imidazo‐fused heterocycles in the ...presence of CsPbBr3 under the irradiation of visible light has been developed. This is the first example of CsPbBr3‐catalyzed aminomethylation of imidazo‐fused heterocycles. The eminent advantage of this work is in that, CsPbBr3 is easily prepared and can be used at least 5 times without obvious reduction in its activity, exhibiting high catalyst economic feature.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The mechanisms of N‐heterocyclic carbene (NHC)‐catalyzed dearomatization reaction of alkyl pyridinium have been intensively studied using the density functional theory (DFT) method. The ...chemoselectivity and stereoselectivity were both analyzed based on the established mechanisms. The computational results showed that the chemoselective C4‐addition occurred before the C2‐addition, which is mainly because the C4 atom was more reactive according to the local reactivity analysis. The stereoselectivity was also investigated, and the C−C bond formation step was identified as the stereoselectivity‐determining step. The C−H⋅⋅⋅F and O−H⋅⋅⋅N interactions are identified as the main factors that govern the stereoselectivity by NCI analysis, and the preferred product was the RS‐configuration. This theoretical investigation would provide a case for understanding and predicting the selectivity of the organocatalytic dearomatization reactions of alkyl pyridinium.
Organocatalysis: The mechanisms of NHC‐catalyzed dearomatization reaction of alkyl pyridinium have been studied by using DFT methods. The potential active sites are successfully predicted by using local reactivity index and the origin of stereoselectivity is disclosed by NCI analysis. This theoretical investigation would aid the understanding and prediction of the selectivity of the organocatalytic dearomatization reactions of alkyl pyridinium.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
A Mn(III)‐mediated radical cyclization reaction of o‐vinylaryl isocyanides and arylboronic acids or diphenylphosphine oxides to access various 2‐functionalized quinolines under mild conditions was ...developed. With the introduction of radical stabilizing substituents (e. g. aryl and methyl group) on vinyl group, this reaction provides a regiospecific 6‐endo‐trig radical cyclization of o‐vinylaryl isocyanides, giving a number of structurally unique and biologically potential 2‐functionalized quinoline derivatives.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The introduction of phosphorus functional groups into the skeleton of thioflavones is an attractive task and of great significance. Herein, a metal‐free visible‐light‐induced radical cascade ...cyclization was developed for the preparation of 2‐phosphorylated thioflavones from methylthiolated alkynones and phosphine oxides. In water as a green reaction medium, a large number of such 2‐phosphorylated thioflavones were prepared, catalyzed by 4CzIPN 1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene under visible‐light irradiation. These reactions could be performed at ambient temperature and feature simple operation, wide reaction scope, and recyclability of aqueous media.
Let there be light: By using water as a reaction medium, a large number of 2‐phosphorylated thioflavones are prepared through the reaction of methylthiolated alkynones and phosphine oxides catalyzed by 4CzIPN 1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene under visible‐light irradiation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A transition‐metal‐free visible‐light‐promoted radical phosphorylation/cyclization of N‐allylbenzamides with phosphine oxides for the synthesis of phosphoryl‐substituted dihydroisoquinolones was ...developed under room temperature. This protocol features mild reaction conditions, simple operation, broad substrate scope as well as scale‐up ability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Glutathione (GSH) serves many cellular functions and plays crucial roles in human pathologies. Simple and sensitive sensors capable of detecting GSH would be useful tools to understand the mechanism ...of diseases. In this work, a rapid fluorescence “switch-on” assay was developed to detect trace amount of GSH based on carbon dots–MnO2 nanocomposites, which was fabricated through in situ synthesis of MnO2 nanosheets in carbon dots colloid solution. Due to the formation of carbon dots–MnO2 nanocomposites, fluorescence of carbon dots could be quenched efficiently by MnO2 nanosheeets through fluorescence resonance energy transfer (FRET). However, the presence of GSH would reduce MnO2 nanosheets to Mn2+ ions and subsequently release carbon dots, which resulted in sufficient recovery of fluorescent signal. This proposed assay demonstrated highly selectivity toward GSH with a detection limit of 300nM. Moreover, this method has also shown sensitive responses to GSH in human serum samples, which indicated its great potential to be used in disease diagnosis. As no requirement of any further functionalization of these as-prepared nanomaterials, this sensing system shows remarkable advantages including very fast and simple, cost-effective as well as environmental-friendly, which suggest that this new strategy could serve as an efficient tool for analyzing GSH level in biosamples.
•A novel fluorescence “switch-on” biosensor is designed for glutathione detection by using carbon dots–MnO2 nanocomposites.•This sensing system displays remarkable properties including simplicity, very short assay time, low-cost as well as nontoxicity.•Results for human serum samples demonstrated that this biosensor is highly applicable for the detection of GSH in biological environments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A simple and efficient decarboxylative radical addition/cyclization strategy was developed, by which a wide range of benzimidazo2,1-aisoquinoline-6(5H)-ones were prepared in one-pot via reaction of ...functionalized 2-arylbenzoimidazoles and carboxylic acids in the presence of K2S2O8/AgNO3 under mild reaction conditions.
