Metallic zinc is an attractive anode material for aqueous rechargeable batteries because of its high theoretical capacity and low cost. However, state-of-the-art zinc anodes suffer from low coulombic ...efficiency and severe dendrite growth during stripping/plating processes, hampering their practical applications. Here we show that eutectic-composition alloying of zinc and aluminum as an effective strategy substantially tackles these irreversibility issues by making use of their lamellar structure, composed of alternating zinc and aluminum nanolamellas. The lamellar nanostructure not only promotes zinc stripping from precursor eutectic Zn
Al
(at%) alloys, but produces core/shell aluminum/aluminum sesquioxide interlamellar nanopatterns in situ to in turn guide subsequent growth of zinc, enabling dendrite-free zinc stripping/plating for more than 2000 h in oxygen-absent aqueous electrolyte. These outstanding electrochemical properties enlist zinc-ion batteries constructed with Zn
Al
alloy anode and K
MnO
cathode to deliver high-density energy at high levels of electrical power and retain 100% capacity after 200 hours.
Atroposelective synthesis of axially chiral biaryls by palladium‐catalyzed C−H olefination, using tert‐leucine as an inexpensive, catalytic, and transient chiral auxiliary, has been realized. This ...strategy provides a highly efficient and straightforward access to a broad range of enantioenriched biaryls in good yields (up to 98 %) with excellent enantioselectivities (95 to >99 % ee). Kinetic resolution of trisubstituted biaryls bearing sterically more demanding substituents is also operative, thus furnishing the optically active olefinated products with excellent selectivity (95 to >99 % ee, s‐factor up to 600).
No attachements: The title reaction employs tert‐leucine as a transient chiral auxiliary and provides efficient access to enantioenriched biaryls in good yields (up to 98 %) with excellent enantioselectivities (up to >99 % ee). Kinetic resolution of trisubstituted biaryls bearing sterically more demanding substituents is also operative, thus furnishing the optically active olefinated products with excellent selectivity (up to >99 % ee, s‐factor up to 600).
Sepsis-associated encephalopathy (SAE) is commonly complicated by septic conditions, and is responsible for increased mortality and poor outcomes in septic patients. Uncontrolled neuroinflammation ...and ischemic injury are major contributors to brain dysfunction, which arises from intractable immune malfunction and the collapse of neuroendocrine immune networks, such as the cholinergic anti-inflammatory pathway, hypothalamic-pituitary-adrenal axis, and sympathetic nervous system. Dysfunction in these neuromodulatory mechanisms compromised by SAE jeopardizes systemic immune responses, including those of neutrophils, macrophages/monocytes, dendritic cells, and T lymphocytes, which ultimately results in a vicious cycle between brain injury and a progressively aberrant immune response. Deep insight into the crosstalk between SAE and peripheral immunity is of great importance in extending the knowledge of the pathogenesis and development of sepsis-induced immunosuppression, as well as in exploring its effective remedies.
The atroposelective synthesis of axially chiral styrenes remains a formidable challenge due to their relatively lower rotational barriers compared to the biaryl atropoisomers. Herein, we describe the ...construction of axially chiral styrenes through PdII‐catalyzed atroposelective C−H olefination, using a bulky amino amide as a transient chiral auxiliary. Various axially chiral styrenes were produced with good yields and high enantioselectivity (up to 95 % yield and 99 % ee). Carboxylic acid derivatives of the resulting axially chiral styrenes showed superior enantiocontrol over the biaryl counterparts in CoIII‐catalyzed enantioselective C(sp3)−H amidation of thioamide. Mechanistic studies suggest that C−H cleavage is the enantioselectivity‐determining step.
Axially chiral styrenes were constructed through a PdII‐catalyzed atroposelective C−H olefination with a bulky amino amide as a transient chiral auxiliary. Various axially chiral styrenes were produced with good yields and high enantioselectivity. Carboxylic acid derivatives of these axially chiral styrenes showed superior enantiocontrol compared to the biaryl counterparts in CoIII‐catalyzed enantioselective C(sp3)−H amidation of ferrocenes.
Biaryl atropisomers are of great importance in natural products, pharmaceuticals, and asymmteric synthesis. The efficient synthesis of these chiral scaffolds with full enantiocontrol and high ...diversity remains challenging. Reported herein is a Pd‐catalyzed atroposelective C−H allylation with tert‐leucine as an efficient catalytic chiral transient auxiliary. A wide range of enantioenriched biaryl aldehydes were prepared in synthetically useful yields with excellent enantioselectivity (up to >99 % ee) through β‐O elimination. The reaction could be carried out on a gram scale without erosion of the ee value. A variety of axially chiral carboxylic acids could be obtained with high enantiopurity. The resulting axially chiral biaryl aldehydes and carboxylic acids might be used in asymmetric synthesis as chiral ligands and/or organocatalysts.
A Pd‐catalyzed atroposelective C−H allylation with allylic surrogates is reported. tert‐Leucine was identified as an efficient catalytic transient chiral auxiliary. A range of enantioenriched biaryls were prepared in synthetically useful yields with enantioselectivities up to >99 % ee through β‐O elimination. The reaction could be scaled up and the products could be further converted into enantiomerically pure axially chiral carboxylic acids.
Dibenzocyclooctadiene lignans are an interesting class of molecules because of their unique structure based on an axially chiral biaryl moiety as well as their significant biological activity. ...Herein, we describe the development of a palladium‐catalyzed atroposelective C−H alkynylation and its application in gram‐scale, stereocontrolled formal syntheses of (+)‐isoschizandrin and (+)‐steganone. tert‐Leucine was identified as an efficient, catalytic transient chiral auxiliary. A wide range of enantiomerically enriched biaryl compounds were prepared by this approach in good yields (up to 99 %) with excellent enantioselectivity (up to >99 % ee).
Locked into position with a Pd key: A palladium‐catalyzed atroposelective C−H alkynylation was developed and applied to gram‐scale, stereocontrolled formal syntheses of (+)‐isoschizandrin (see scheme) and (+)‐steganone. tert‐Leucine was identified as an efficient catalytic transient chiral auxiliary for this transformation, which enabled the preparation of a wide range of enantiomerically enriched biaryl compounds in good yields.
The discovery of proper ligands to simultaneously modulate the reactivity and effectively control the stereoselectivity is a central topic in the field of enantioselective C−H activation. Herein, we ...reported the synthesis of axially chiral biaryls by Pd‐catalyzed atroposelective C−H olefination. A novel chiral spiro phosphoric acid, STRIP, was identified as a superior ligand for this transformation. A broad range of axially chiral quinoline derivatives were synthesized in good yields with excellent enantioselectivities (up to 98 % ee). Density functional theory was used to gain a theoretical understanding of the enantioselectivities in this reaction.
The discovery of proper ligands to simultaneously modulate the reactivity and effectively control the stereoselectivity is a central topic in the field of enantioselective C−H activation. Herein, the synthesis of axially chiral biaryls by Pd‐catalyzed atroposelective C−H olefination is reported. A broad range of axially chiral quinoline derivatives were synthesized in good yields with excellent enantioselectivities (up to 98 % ee).
Chiral aldehyde catalysis opens new avenues for the activation of simple amines. However, the lack of easy access to structurally diverse chiral aldehyde catalysts has hampered the development of ...this cutting‐edge field. Herein, we report a Pd‐catalyzed atroposelective C−H naphthylation with 7‐oxabenzonorbornadienes for the preparation of axially chiral biaryls with excellent enantioselectivities (up to >99 % ee). This reaction is scalable and robust, which serves as a key step to provide a rapid access to axially chiral aldehyde catalysts through a three‐step C−H functionalization sequence. These chiral aldehydes exhibit better activities and enantioselectivities than the previously reported organocatalysts in the asymmetric activation of glycine derived amides and dipeptides. Moreover, preliminary investigation also discloses that the aldehyde catalyst can effectively override the intrinsic facial selectivity of chiral dipeptide substrates, showcasing the strong chiral induction ability of this type of novel aldehyde catalysts.
A concise synthetic route to chiral aldehyde catalysts with Pd‐catalyzed atroposelective C−H naphthylation as a key reaction is reported. These chiral aldehyde catalysts were successfully employed as ligands in the asymmetric activation of glycine esters enabling a higher level of asymmetric induction and reaction activity. A wide range of enantioenriched biaryls were prepared in synthetically useful yields with excellent enantioselectivities (up to >99 % ee).
The atroposelective synthesis of atropisomers with vicinal diaxes remains rare and challenging, due to the steric influence between the two axes and their unique topology. Herein, we disclose a ...single‐step construction of atropisomers with vicinal C−C and C−N chiral diaxes by cyclopentadiene (Cp)‐free cobalt‐catalyzed intramolecular atroposelective C−H annulation, providing the desired diaxial atropisomers of unique structures with decent stereocontrols of both axes (up to >99 % ee and 70 : 1 dr). The optically pure products bearing fluorophores show circular polarized luminescence (CPL) properties, being candidate materials for potential CPL applications. Atropisomerization experiments and density function theory (DFT) calculations are conducted to study the rotational barriers and rotation pathways of the diaxes.
A single‐step construction of atropisomers with vicinal C−C and C−N chiral diaxes by cyclopentadiene (Cp)‐free cobalt‐catalyzed intramolecular atroposelective C−H annulation with decent stereocontrols (up to >99 % ee and 70/1 dr) was reported. Atropisomerization experiments and DFT calculations are done to study the rotational barriers and pathways of the diaxes.
Designing highly active and robust electrocatalysts for oxygen evolution reaction (OER) is crucial for many renewable energy storage and conversion devices. Here, self‐supported monolithic hybrid ...electrodes that are composed of bimetallic cobalt–molybdenum nitride nanosheets vertically aligned on 3D and bicontinuous nanoporous gold (NP Au/CoMoNx) are reported as highly efficient electrocatalysts to boost the sluggish reaction kinetics of water oxidation in alkaline media. By virtue of the constituent CoMoNx nanosheets having large accessible CoMoOx surface with remarkably enhanced electrocatalytic activity and the nanoporous Au skeleton facilitating electron transfer and mass transport, the NP Au/CoMoNx electrode exhibits superior OER electrocatalysis in 1 m KOH, with low onset overpotential (166 mV) and Tafel slope (46 mV dec−1). It only takes a low overpotential of 370 mV to reach ultrahigh current density of 1156 mA cm−2, ≈140‐fold higher than free CoMoNx nanosheets. The electrocatalytic performance makes it an attractive candidate as the OER catalyst in the water electrolysis.
A flexible Co–Mo–N/Au electrode, which is composed of bimetallic cobalt–molybdenum nitride nanosheets vertically aligned on nanoporous gold, is successfully developed as a robust oxygen evolution reaction (OER) electrocatalyst in alkaline media. This electrode exhibits enhanced OER activity and durability by virtue of the CoMoNx nanosheets having large accessible CoMoOx surface and the nanoporous Au facilitating electron transfer and mass transport.
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