Multicomponent Reductive Coupling for Selective Access to Functional γ-Lactams by a Single-Atom Cobalt Catalyst.

Despite their significant importance to numerous fields, the difficulties in direct and diverse synthesis of α-hydroxy-γ-lactams pose substantial obstacles to their practical applications. Here, we designed a nitrogen and TiO2 co-doped graphitic carbon-supported material with atomically dispersed cobalt sites (CoSA-N/NC-TiO2), which was successfully applied as a multifunctional catalyst to establish a general method for direct construction of α-hydroxy-γ-lactams from cheap and abundant nitro(hetero)arenes, aldehydes, and H2O with alkynoates. The striking features of operational simplicity, broad substrate and functionality compatibility (>100 examples), high step and atom efficiency, good selectivity, and exceptional catalyst reusability highlight the practicality of this new catalytic transformation. Mechanistic studies reveal that the active CoN4 species and the dopants exhibit a synergistic effect on the formation of key acid-masked nitrones; their subsequent nucleophilic addition to the alkynoates followed by successive reduction, alkenyl hydration, and intramolecular ester ammonolysis delivers the desired products. In this work, the concept of reduction interruption leading to new reaction route will open a door to further develop useful transformations by rational catalyst design.

Reduction-Specified Coupling Reactions of Nitroarenes by Heterogeneous Cobalt Catalysis.

The in-depth study on reduction-specified coupling reactions of the nitroarenes by heterogeneous cobalt catalysis opens a door for diversified syntheses of functional N-containing molecules. Guided by the structure-function relationship of heterogeneous materials, rational design of nano-catalysts can effectively regulate the routes of organic reactions. Precise transformation of the intermediates generated during the nitroarene reduction with a suitable nano-catalyst is a promising way to develop new tandem reactions, and to synthesize structurally novel compounds that are of difficult access with the conventional approaches.

Cu2+@metal-organic framework-derived amphiphilic sandwich catalysts for enhanced hydrogenation selectivity of ketenes at the oil-water interface.

Selective catalysis has always been an essential process for manufacturing various fine chemicals, such as food additives, pharmaceuticals and perfumes. Practically, pure target products are difficult to obtain even after complex purification procedures during industrial production. The development of a cost-effective, highly chemoselective and long-life catalyst may be an attractive solution, but such a catalyst is elusive. Herein, a novel class of amphiphilic N-doped carbon (NC), featuring graphitic carbon (GC) and highly dispersed Cu@Co NPs, was fabricated via simple calcination of a Cu2+-doped bimetallic metal-organic framework (MOF) precusor directly. Compared with monometallic Co@GC/NC, the side reaction of CO bond hydrogenation is obviously restrained, and thus, pure target product can be systematically obtained by Cu@Co@GC/NC, highlighting the high selectivity of Cu. More importantly, an amphiphilic characteristic in Cu@Co@GC/NC is a significant knob to integrate organic substrates with water very well. This amphiphilic material shows great potential as a field-deployable pathway for dispersible metal catalysts in organic systems.

Reductive Coupling of Nitroarenes and HCHO for General Synthesis of Functional Ethane-1,2-diamines by a Cobalt Single-Atom Catalyst.

Despite the extensive applications, selective and diverse access to N,N'-diarylethane-1,2-diamines remains, to date, a challenge. Here, by developing a bifunctional cobalt single-atom catalyst (CoSA-N/NC), we present a general method for direct synthesis of such compounds via selective reductive coupling of cheap and abundant nitroarenes and formaldehyde, featuring good substrate and functionality compatibility, an easily accessible base metal catalyst with excellent reusability, and high step and atom efficiency. Mechanistic studies reveal that the N-anchored cobalt single atoms (CoN4) serve as the catalytically active sites for the reduction processes, the N-doped carbon support enriches the HCHO to timely trap the in situ formed hydroxyamines and affords the requisite nitrones under weak alkaline conditions, and the subsequent inverse electron demand 1,3-dipolar cycloaddition of the nitrones and imines followed by hydrodeoxygenation of the cycloadducts furnishes the products. In this work, the concept of catalyst-controlled nitroarene reduction to in situ create specific building blocks is anticipated to develop more useful chemical transformations.

Interleukin-17 is involved in neuropathic pain and spinal synapse plasticity on mice.

Neuropathic pain seriously affects people's life, but its mechanism is not clear. Interleukin-17 (IL-17) is a proinflammation cytokine and involved in pain regulation. Our previous study found that IL-17 markedly enhanced the excitatory activity of spinal dorsal neurons in mice spinal slices. The present study attempts to explore if IL-17 contributes to neuropathic pain and spinal synapse plasticity. A model of spared nerve injury (SNI) was established in C57BL/6 J mice and IL-17a mutant mice. The pain-like behaviors was tested by von Frey test and dynamic mechanical stimuli, and the expression of IL-17 and its receptor, IL-17RA, was detected by immunohistochemical staining. C-fiber evoked field potentials were recorded in vivo. In the spinal dorsal horn, IL-17 predominantly expressed in the superficial spinal astrocytes and IL-17RA expressed mostly in neurons and slightly in astrocytes. The SNI-induced static and dynamic allodynia was significantly prevented by pretreatment of neutralizing IL-17 antibody (intrathecal injection, 2 µg/10 µL) and attenuated in IL-17a mutant mice. Post-treatment of IL-17 neutralizing antibody also partially relieved the established mechanical allodynia. Moreover, spinal long-term potentiation (LTP) of C-fiber evoked field potentials, a substrate for central sensitization, was suppressed by IL-17 neutralizing antibody. Intrathecal injection of IL-17 recombinant protein (0.2 µg/10 µL) mimicked the mechanical allodynia and facilitated the spinal LTP. These data implied that IL-17 in the spinal cord played a crucial role in neuropathic pain and central sensitization.

Utilizing Nitroarenes and HCHO to Directly Construct Functional N-Heterocycles by Supported Cobalt/Amino Acid Relay Catalysis.

Due to the generation of multiple intermediates during the nitroarene reduction, precise interception of single one to develop tandem reactions involving both C-C and C-N bond formations still remains a significant challenge. Herein, the relay catalysis of a supported bifunctional cobalt catalyst with l-proline has been successfully applied to establish a bran-new reductive annulation reaction of nitroarenes and formaldehyde, which enables direct and diverse construction of both symmetrical and unsymmetrical 1,3-diaryl imidazolines. It proceeds with operational simplicity, good substrate and functionality compatibility, and excellent step and atom-efficiency. Mechanistic studies reveal that the Co-catalyst exhibits a synergistic effect on the formation of key N-hydroxy imine, and the l-proline subsequently facilitates the key C-C bond formation. The current work opens a door to develop useful transformations with nitroarenes by reduction-interrupted strategy.

Novel CoNi-metal-organic framework crystal-derived CoNi@C: synthesis and effective cascade catalysis.

Evaluating the catalytic influence of metal sites on derivates obtained from the calcination of metal-organic frameworks (MOFs) is very important for the rational construction of novel MOFs. Based on this catalytic functional guidance, two new Co-MOF and CoNi-MOF crystals were designed and synthesized, and further pyrolyzed to obtain corresponding porous carbon-based catalysts. Interestingly, the derivates exhibited better catalytic performance toward the tandem reaction of dehydrogenation of NH3BH3 and subsequent hydrogenation reduction of nitro/olefin compounds than those of the CoNi-ZIF (a star MOF)-derived CoNi@carbon and most metal catalysts. Significantly, the CoNi@C maintained excellent activity, even after 30 cycles, demonstrating its great longevity and durability, which are especially important for the practical application of metal catalysts in industrial catalysis.

Involvement of Interleukin-10 in Analgesia of Electroacupuncture on Incision Pain.

OBJECTIVE: Postincision pain often occurs after surgery and is an emergency to be treated in clinic. Electroacupuncture (EA) is a Chinese traditional treatment widely used to cure acute or chronic pain, but its mechanism is not clear. Interleukin-10 (IL-10) is a powerful anti-inflammatory cytokine that shows neuroprotective effects in inflammation and injury in the CNS. The present study attempts to reveal that IL-10 is crucial for EA analgesia on postincision pain. METHODS: A model of incision pain was established in C57BL/6J mice. The pain threshold was detected by behavioral test, and the expression of IL-10 and its receptor was detected by an immunohistochemical method. C-fiber-evoked field potentials were recorded by in vivo analysis. RESULTS: The mechanical allodynia induced by paw incision was significantly inhibited by pretreatment of EA in mice. Intrathecal injection of IL-10 neutralizing antibody (2 µg/10 µL) but not intraplantar injection (10 µg/10 µL) reversed the analgesia of EA. The upregulations of IL-10 mRNA and protein were induced by EA at 6 h and 1 d after incision, respectively. Spinal long-term potentiation (LTP), a substrate for central sensitization, was also suppressed by EA with IL-10. IL-10 recombinant protein (1 µg/10 µL, i.t.) mimicked the analgesia of EA on mechanical allodynia and inhibition on the spinal LTP. Posttreatment of EA after incision also transitorily relieved the mechanical allodynia, which can be blocked by spinal IL-10 antibody. IL-10 and its receptor, IL-10RA, are predominantly expressed in the superficial spinal astrocytes. CONCLUSIONS: These results suggested that pretreatment of EA effectively prevented postincision pain and IL-10 in spinal astrocytes was critical for the analgesia of EA and central sensitization.

Three-Shell Cu@Co@Ni Nanoparticles Stabilized with a Metal-Organic Framework for Enhanced Tandem Catalysis.

Transition-metal catalysts, particularly featuring a triple-layered core-shell structure, are very promising for practical application; however, reports on their synthesis and catalytic application for a cascade reaction were very rare. In this work, tiny Cu@Co@Ni core-shell nanoparticles (∼3.3 nm) containing Cu core, Co middle shell, and Ni outer shell stabilized by metal-organic framework (MOF) were successfully synthesized to give a quadruple-layered Cu@Co@Ni/MOF at moderate conditions. The catalyst exhibited superior catalytic performance toward the in situ hydrogenation of nitroarenes using the H2 generated from the hydrolysis of ammonia borane (NH3BH3) under mild conditions. Interestingly, the Cu@Co@Ni/MOF also showed excellent catalytic activity toward CO oxidation reaction, which outperforms those of noble-metal catalysts. To our knowledge, this is the first report on transition-metal nanoparticles with a three-layered core-shell structure stabilized by MOF as a cooperative catalyst for cascade reaction and CO oxidation.