Recent years have witnessed the growing interest in the remote functionalization of alkenes for it offers a strategy to activate the challenging C–H bonds distant from the initiation point via alkene isomerization/functionalization. However, the catalytic enantioselective isomerization/functionalization with one single transition metal catalyst remains rare. Here we report a highly regio- and enantioselective cobalt-catalyzed remote C–H bond borylation of internal alkenes via sequential alkene isomerization/hydroboration. A chiral ligand featured twisted pincer, anionic, and non-rigid characters is designed and used for this transformation. This methodology, which is operationally simple using low catalyst loading without additional activator, shows excellent enantioselectivity and can be used to convert various internal alkenes with regio- and stereoisomers to valuable chiral secondary organoboronates with good functional group tolerance.

Conspectus Transition metal catalyzed asymmetric hydrofunctionalization of readily available unsaturated hydrocarbons presents one of the most straightforward and atom-economic protocols to access valuable optically active products. For decades, noble transition metal catalysts have laid the cornerstone in this field, on account of their superior reactivity and selectivity. In recent years, from an economical and sustainable standpoint, first-row, earth-abundant transition metals have received considerable attention, due to their high natural reserves, affordable costs, and low toxicity. Meanwhile, the earth-abundant metal catalyzed hydrofunctionalization reactions have also gained much interest and been investigated gradually. However, since chiral ligand libraries for earth-abundant transition-metal catalysis are limited to date, the development of highly enantioselective versions remains a significant challenge. This Account summarizes our recent efforts in developing suitable chiral ligands for iron and cobalt catalysts and their applications in the highly enantioselective hydrofunctionalization reactions (hydroboration and hydrosilylation) of alkenes and alkynes. In ligand design, we envisioned that chiral unsymmetric NNN-tridentate (UNT) ligand scaffolds could promote these enantioselective transformations with earth-abundant metals. Therefore, several types of chiral UNT ligands were designed and prepared in our laboratory, utilizing readily available natural amino acids as chiral sources. In the very beginning, chiral oxazoline iminopyridine (OIP) ligands were proposed and investigated through the rational combination of nitrogen-containing ligand scaffolds. After a systematic survey of the ligand effects, the imine moiety in the rigid OIP ligands was replaced by a conformationally more flexible amine unit, leading to the construction of reactive oxazoline aminoisopropylpyridine (OAP) ligands. Subsequently, imidazoline iminopyridine (IIP) and thiazoline iminopyridine (TIP) ligands were prepared by altering the oxygen atom of oxazoline with nitrogen and sulfur linkers, respectively. To further expand the chiral ligand library, other tridentate ligands containing a twisted pincer, anionic, and nonrigid backbone were also designed and synthesized, including iminophenyl oxazolinyl phenylamine (IPOPA) and imidazoline phenyl picolinamide (ImPPA). The efficacy of these chiral UNT ligands for asymmetric induction in iron and cobalt catalysis has been demonstrated through asymmetric hydrofunctionalization of alkenes and asymmetric sequential hydrofunctionalization of alkynes, which exhibit excellent reactivity as well as high chemo-, regio-, and stereoselectivity with broad functional group tolerance. Notably, highly regio- and enantioselective hydrofunctionalization of challenging substrates, such as 1,1-disubstituted aryl alkenes and terminal aliphatic alkenes, was also achieved. Furthermore, the development of asymmetric sequential isomerization/hydroboration of internal alkenes and sequential hydrofunctionaliz...

Using a three-dimensional (3D) Li-ion conducting ceramic network, such as Li7La3Zr2O12 (LLZO) garnet-type oxide conductor, has proved to be a promising strategy to form continuous Li ion transfer paths in a polymer-based composite. However, the 3D network produced by brittle ceramic conductor nanofibers fails to provide sufficient mechanical adaptability. In this manuscript, we reported a new 3D ion-conducting network, which is synthesized from highly loaded LLZO nanoparticles reinforced conducting polymer nanofibers, by creating a lightweight continuous and interconnected LLZO-enhanced 3D network to outperform conducting heavy and brittle ceramic nanofibers to offer a new design principle of composite electrolyte membrane featuring all-round properties in mechanical robustness, structural flexibility, high ionic conductivity, lightweight, and high surface area. This composite-nanofiber design overcomes the issues of using ceramic-only nanoparticles, nanowires, or nanofibers in polymer composite electrolyte, and our work can be considered as a new generation of composite electrolyte membrane in composite electrolyte development.

ideally stores five times more energy per mass (1675 mAh g −1 ) than intercalationtype cathodes by multielectron reactions of sulfur, namely S 8 + 16 e − + 16 Li + ⇌ 8 Li 2 S, [8,9] and leads to extensive researches on Li-S batteries.Nevertheless, the development of Li-S batteries is plagued by three issues: (1) the sluggish electrical conductivities of sulfur (σ = 5 × 10 −30 S cm −1 ) and its end products (Li 2 S, σ = 1 × 10 −13 S cm −1 ) lead to slow conversion from soluble lithium polysulfides (LiPSs, namely Li 2 S x , 4 ≤ x ≤ 8) to solid Li 2 S 2 /Li 2 S; (2) the hydrophilic LiPS species are inclined to shuttle through porous separator and deposit at Li anode as Li 2 S which is difficult to be reused owing to the high activation energy [10][11][12][13] ; (3) the shuttling effect of polysulfides causes severe self-discharge, continuous energy loss and unsatisfactory energy density. [14][15][16] Reconstructing separators architecture is an effective strategy to ameliorate the aforementioned issues. [17][18][19] Carbon materials with a high specific surface area are introduced to the separator surface to physically block LiPS and accelerate its conversion due to the high conductivity (σ = 9 × 10 1 -5 × 10 3 S m −1 ), [20] but porous carbon shows limited capability to confine LiPS owing to the feeble van der Waals adsorption. [21,22] Polar compounds, such as metal compounds (MA, where M is metal, and A is oxygen, nitrogen, or sulfur), are promising materials to bond to LiPS through surface M-S or A-Li bonding, which prevents the shuttling effect and changes the reduction pathway of LiPS with decreased the redox energy barrier. [23,24] However, the strong A-Li bonding of ≈2 eV impedes Li + ion transport which delays the reaction kinetics of LiPSs. [25] In addition, most of them own complex design processes. [26] Recent studies show that the low cost and natural abundance lamellar clays own much lower Li-ion diffusion barrier (such as lithium-montmorillonite (0.15 eV), MA materials (ZnS (0.494 eV), MgO (0.45 eV), Al 2 O 3 (1.22 eV), and CeO 2 (0.66eV)), [27,28] which allows free lithium-ion diffusion in the sulfur cathode and gives rise to improved electrochemical performances of Li-S batteries. Unfortunately, these lamellar clays modified structures still show unsatisfactory rate performances for practical application. [29] Hence, it is necessary to further develop optimized lamellar clays structure for high-rate Li-S batteries.

A cobalt-catalyzed asymmetric hydroboration of styrenes using an imidazoline phenyl picoliamide (ImPPA) ligand was first reported to deliver the valuable chiral secondary organoboronates with good functional tolerance and high enantioselectivity (up to >99% ee). This protocol is operationally simple without any activator. Particularly, this method can be applied in the asymmetric hydroboration of allylamine to afford 1,3-amino alcohol, which is a key intermediate for the synthesis of fluoxetine and atomoxetine. Furthermore, control experiments, isotopic labeling experiments, and qualitative and quantitative kinetic studies were also conducted to figure out the primary mechanism.