Reported herein is an unprecedented synthesis of C3‐fluorinated oxindoles through cross‐dehydrogenative coupling of C(sp3)‐H and C(sp2)‐H bonds from malonate amides. Under the unique and mild ...electrochemical conditions, the requisite oxidant and base are generated in a continuous fashion, allowing the formation of the base‐ and heat‐sensitive 3‐fluorooxindoles in high efficiency with broad substrate scope. The synthetic usefulness of the electrochemical method is further highlighted by its easy scalability and the diverse transformations of the electrolysis product.
C−H functionalization: A ferrocene‐catalyzed electrochemical cross‐coupling reaction of C(sp3)‐H and C(sp2)‐H centers has been developed to give access to C3‐fluorinated oxindoles using fluorinated malonate amides. The electrosynthetic method is characterized by mild reaction conditions, broad substrate scope, high functional group tolerance, and easy scalability.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The direct functionalization of allylic C−H bonds with nucleophiles minimizes pre‐functionalization and converts inexpensive, abundantly available materials to value‐added alkenyl‐substituted ...products but remains challenging. Here we report an electrocatalytic allylic C−H alkylation reaction with carbon nucleophiles employing an easily available cobalt–salen complex as the molecular catalyst. These C(sp3)−H/C(sp3)−H cross‐coupling reactions proceed through H2 evolution and require no external chemical oxidants. Importantly, the mild conditions and unique electrocatalytic radical process ensure excellent functional group tolerance and substrate compatibility with both linear and branched terminal alkenes. The synthetic utility of the electrochemical method is highlighted by its scalability (up to 200 mmol scale) under low loading of electrolyte (down to 0.05 equiv) and its successful application in the late‐stage functionalization of complex structures.
An electrocatalytic allylic C−H alkylation reaction with carbon nucleophiles is reported, which employs an easily available cobalt–salen complex as the molecular catalyst. The method is characterized by its excellent functional group tolerance, substrate compatibility with both linear and branched terminal alkenes, and scalability (up to 200 mmol scale) with a low loading of electrolyte (down to 0.05 equiv).
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Lithium-sulfur (Li-S) batteries have emerged as promising energy storage devices due to their high theoretical specific energy densities; their practical applications, however, have been restricted ...due to their poor cycling stability arising from the shuttle effect of the S cathode and dangerous Li dendrite growth. S and Li can be encapsulated into porous framework hosts to address these issues. Metal-organic frameworks (MOFs)/covalent-organic frameworks (COFs) have shown great potential due to their tunable frameworks, structural diversity, and functional versatility. In this review, the applications of MOFs/COFs for Li-S batteries in terms of the sulfur hosts, electrolyte containers, separators, and Li dendrite blocking barriers are systematically summarized. A short conclusion and outlook regarding future research opportunities for pristine MOFs/COFs for Li-S batteries are also provided.
Recent advances of MOFs/COFs in research towards Li-S batteries in terms of cathodes, electrolytes, separators, and Li anodes have been fully investigated.
Electrolyte engineering via fluorinated additives is promising to improve cycling stability and safety of high‐energy Li‐metal batteries. Here, an electrolyte is reported in a porous lithium fluoride ...(LiF) strategy to enable efficient carbonate electrolyte engineering for stable and safe Li‐metal batteries. Unlike traditionally engineered electrolytes, the prepared electrolyte in the porous LiF nanobox exhibits nonflammability and high electrochemical performance owing to strong interactions between the electrolyte solvent molecules and numerous exposed active LiF (111) crystal planes. Via cryogenic transmission electron microscopy and X‐ray photoelectron spectroscopy depth analysis, it is revealed that the electrolyte in active porous LiF nanobox involves the formation of a high‐fluorine‐content (>30%) solid electrolyte interphase layer, which enables very stable Li‐metal anode cycling over one thousand cycles under high current density (4 mA cm−2). More importantly, employing the porous LiF nanobox engineered electrolyte, a Li || LiNi0.8Co0.1Mn0.1O2 pouch cell is achieved with a specific energy of 380 Wh kg−1 for stable cycling over 80 cycles, representing the excellent performance of the Li‐metal pouch cell using practical carbonate electrolyte. This study provides a new electrolyte engineering strategy for stable and safe Li‐metal batteries.
Electrolyte engineering via fluorinated additives is promising to improve the cycling stability and safety of high‐energy Li‐metal batteries. The electrolyte in an active porous LiF nanobox involves the formation of a high‐fluorine‐content (>30%) solid electrolyte interphase layer to achieve a ≈3.5 Ah Li || LiNi0.8Co0.1Mn0.1O2 pouch cell with a specific energy of 380 Wh kg−1 under a practical carbonate electrolyte.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
During the outbreak of coronavirus disease 2019 (COVID-19), consistent and considerable differences in disease severity and mortality rate of patients treated in Hubei province compared to those in ...other parts of China have been observed. We sought to compare the clinical characteristics and outcomes of patients being treated inside and outside Hubei province, and explore the factors underlying these differences.
Collaborating with the National Health Commission, we established a retrospective cohort to study hospitalised COVID-19 cases in China. Clinical characteristics, the rate of severe events and deaths, and the time to critical illness (invasive ventilation or intensive care unit admission or death) were compared between patients within and outside Hubei. The impact of Wuhan-related exposure (a presumed key factor that drove the severe situation in Hubei, as Wuhan is the epicentre as well the administrative centre of Hubei province) and the duration between symptom onset and admission on prognosis were also determined.
At the data cut-off (31 January 2020), 1590 cases from 575 hospitals in 31 provincial administrative regions were collected (core cohort). The overall rate of severe cases and mortality was 16.0% and 3.2%, respectively. Patients in Hubei (predominantly with Wuhan-related exposure, 597 (92.3%) out of 647) were older (mean age 49.7
44.9 years), had more cases with comorbidity (32.9%
19.7%), higher symptomatic burden, abnormal radiologic manifestations and, especially, a longer waiting time between symptom onset and admission (5.7
4.5 days) compared with patients outside Hubei. Patients in Hubei (severe event rate 23.0%
11.1%, death rate 7.3%
0.3%, HR (95% CI) for critical illness 1.59 (1.05-2.41)) have a poorer prognosis compared with patients outside Hubei after adjusting for age and comorbidity. However, among patients outside Hubei, the duration from symptom onset to hospitalisation (mean 4.4
4.7 days) and prognosis (HR (95%) 0.84 (0.40-1.80)) were similar between patients with or without Wuhan-related exposure. In the overall population, the waiting time, but neither treated in Hubei nor Wuhan-related exposure, remained an independent prognostic factor (HR (95%) 1.05 (1.01-1.08)).
There were more severe cases and poorer outcomes for COVID-19 patients treated in Hubei, which might be attributed to the prolonged duration of symptom onset to hospitalisation in the epicentre. Future studies to determine the reason for delaying hospitalisation are warranted.
Transition metal catalyzed C−H phosphorylation remains an unsolved challenge. Reported methods are generally limited in scope and require stoichiometric silver salts as oxidants. Reported here is an ...electrochemically driven RhIII‐catalyzed aryl C−H phosphorylation reaction that proceeds through H2 evolution, obviating the need for stoichiometric metal oxidants. The method is compatible with a variety of aryl C−H and P−H coupling partners and particularly useful for synthesizing triarylphosphine oxides from diarylphosphine oxides, which are often difficult coupling partners for transition metal catalyzed C−H phosphorylation reactions. Experimental results suggest that the mechanism responsible for the C−P bond formation involves an oxidation‐induced reductive elimination process.
Electric cell: Reported herein is an electrochemically driven RhIII‐catalyzed aryl C−H phosphorylation reaction which proceeds through H2 evolution. The method is compatible with a variety of aryl C−H and P−H coupling partners and particularly useful for synthesizing triarylphosphine oxides from diarylphosphine oxides. Experimental results suggest that the mechanism responsible for the C−P bond formation involves an oxidation‐induced reductive elimination process. DG=directing group.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The intramolecular C(sp3)-H/C(sp2)-H cross-coupling of 1,3-dicarbonyl compounds has been achieved through Cp2Fe-catalyzed electrochemical oxidation. The key to the success of these dehydrogenative ...cyclization reactions is the selective activation of the acidic α-C-H bond of the 1,3-dicarbonyl moiety to generate a carbon-centered radical.
Dehydrogenative annulation under oxidizing reagent‐free conditions is an ideal strategy to construct cyclic structures. Reported herein is an unprecedented synthesis of pyrrolidine and ...tetrahydropyridine derivatives through electrochemical dehydrogenative annulation of N‐allyl amides with 1,3‐dicarbonyl compounds. The electrolytic method employs an organic redox catalyst, which obviates the need for oxidizing reagents and transition‐metal catalysts. In these reactions, the N‐allyl amides serve as a four‐atom donor to react with dimethyl malonate to give pyrrolidines by a (4+1) annulation, or with β‐ketoesters to afford tetrahydropyridine derivatives by a (4+2) annulation.
Powered by electricity: Unprecedented dehydrogenative annulation reactions of N‐allyl amides with 1,3‐dicarbonyl compounds have been developed for the efficient and modular synthesis of pyrrolidine and tetrahydropyridine derivatives. These electricity‐powered reactions employ a phenothiazine‐based organic redox catalyst, allowing the reactions to proceed under transition‐metal‐ and oxidizing‐reagent‐free conditions.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Besides epitaxial mismatch that can be accommodated by lattice distortions and/or octahedral rotations, ferroelectric-ferromagnetic interfaces are affected by symmetry mismatch and subsequent ...magnetic ordering. Here, we have investigated La
Sr
MnO
(LSMO) samples with varying underlying unit cells (uc) of BaTiO
(BTO) layer on (001) and (110) oriented substrates in order to elucidate the role of symmetry mismatch. Lattice mismatch for 3 uc of BTO and symmetry mismatch for 10 uc of BTO, both associated with local MnO
octahedral distortions of the (001) LSMO within the first few uc, are revealed by scanning transmission electron microscopy. Interestingly, we find exchange bias along the in-plane 110/100 directions only for the (001) oriented samples. Polarized neutron reflectivity measurements confirm the existence of a layer with zero net moment only within (001) oriented samples. First principle density functional calculations show that even though the bulk ground state of LSMO is ferromagnetic, a large lattice constant together with an excess of La can stabilize an antiferromagnetic LaMnO
-type phase at the interface region and explain the experimentally observed exchange bias. Atomic scale tuning of MnO
octahedra can thus be made possible via symmetry mismatch at heteroepitaxial interfaces. This aspect can act as a vital parameter for structure-driven control of physical properties.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
PDF
