ZrOCl2·8H2O catalyzed solvent-free synthesis of isobenzofuran-1（3H）-ones

ZrOCl₂·8H₂O catalyzed environmentally benign synthesis of isobenzofuran-1（3H）-ones are described.ZrOCl₂·8H₂O appeared to be an excellent catalyst for the condensation and reactions.Reaction of phthalaldehydic acid（2-carboxybenzaldehyde） with methylaryl and cyclic ketones was initiated by condensation and occurred in one step providing excellent yields（90-98%）.     

A family of novel bifunctional organocatalysts:Highly enantioselective alcoholysis of meso cyclic anhydrides and its application for synthesis of the key intermediate of P2X7 receptor antagonists

A family of novel squaramides/sulfamides based on 1,2-alkamine was developed as chiral bifunctional catalysts to promote the asymmetric alcoholysis of meso cyclic anhydrides.The hemiesters were obtained in high yield with up to 93%ee.The usefulness of this methodology was demonstrated in the asymmetric synthesis of the key intermediate of P2X₇ receptor antagonists.     

Effect of Solvents on Oxidation of 1,1′-Bi-2-naphthol

A novel biomimetic catalyst of complex Cu(p-OTs)2/ethanolamine(1∶1) was used to oxidize 1,1′-bi-2-naphthol into xanthene derivatives with a relative high yield in a mixed solvents of dimethyl sulfoxide(DMSO) and CH3OH. The studies on the effect of some solvents on the yield of xanthene derivatives indicates that the yield reduces dramatically with the increase of the content of H2O in the mixed solvents of H2O and DMSO. No product can be obtained when the content of H2O is up to 70%. The cyclic voltammetric study demonstrated that the copper ion in complex Cu(p-OTs)2/ethanolamine(1∶1) is reduced via a two-step one-electron reduction process from Cu(Ⅱ) to Cu in the mixture of DMSO and H2O. Water as a poor solvent in respect to the reactants probably hampered the coordination of 1,1′-bi-2-naphthol to copper/amine complex and led to the insufficient catalytic efficiency of complex Cu(p-OTs)2/ethanolamine(1∶1).     

Cu-clusters nodes of 2D metal-organic frameworks as a cost-effective noble-metal-free cocatalyst with high atom-utilization efficiency for efficient photocatalytic hydrogen evolution

Several 2D nanosheets of porphyrin MOFs with various transition-metal clusters as metal nodes were prepared via a simple solvothermal method to apply in the photocatalytic hydrogen evolution,in which the hydrogen production rate of the optimal NS-Cu was as high as 15.39 mmol g^-1h^-1.A series of experimental technologies especially cyclic voltammetry （CV） and Mott-Schottky （M-S） had been adopted to investigate the charge-transfer property of photo-generated electron-hole pair...     

Conversion of ethanol to 1,3-butadiene over Ag-ZrO2/SiO2 catalysts:The role of surface interfaces

A series of Ag-ZrO₂/SiO₂ catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and selectivity.According to the results of detailed characterizations(e.g.CO/pyridine-DRIFTS,XPS,TEM,NH3-TPD,and ¹H MAS NMR),it was found that the Ag-O-Si interfaces significantly enhanced the dehydrogenation of ethanol while the presence of ZrO₂ improved the interaction between Ag and ZrO₂/SiO₂,creating more Ag^δ+active sites.The high dispersion of ZrO₂ on SiO₂ generated abundant Zr-O-Si interfaces with medium and weak Lewis acidity,promoting the condensation of acetaldehyde to crotonaldehyde.These Zr-O-Si interfaces in close interaction with Ag^δ+species played a critical role in the enhanced H transfer during the MPV reduction of crotonaldehyde to crotyl alcohol.The synergies among the interfaces resulted in retarded ethanol dehydration reactivity,balanced ethanol dehydrogenation and condensation reactions,and a subsequent high 1,3-butadiene yield.     

Effect of Solvents on Oxidation of 1, 1′-Bi-2-naphthol

A novel biomimetic catalyst of complex Cu (p-OTs)2/ethanolamine (1 : 1 ) was used to oxidize 1, 1′-bi-2naphthol into xanthene derivatives with a relative high yield in a mixed solvents of dimethyl sulfoxide (DMSO) and CH3OH. The studies on the effect of some solvents on the yield of xanthene derivatives indicates that the yield reduces dramatically with the increase of the content of H2O in the mixed solvents of H2O and DMSO. No product can be obtained when the content of H2O is up to 70%. The cyclic voltammetric study demonstrated that the copper ion in complex Cu(p-OTs)2/ethanolamine(1:1) is reduced via a twostep one-electron reduction process from Cu (Ⅱ) to Cu in the mixture of DMSO and H2O. Water as a poor solvent in respect to the reactants probably hampered the coordination of 1, 1′-bi-2-naphthol to copper/amine complex and led to the insufficient catalytic efficiency of complex Cu(p-OTs),/ethanolamine(1:1).     

Enhancing thermodynamic stability of single-crystal Ni-rich cathode material via a synergistic dual-substitution strategy

Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity. However, the poor thermodynamic stability(including cyclic performance and safety performance or thermal stability) will restrain their wide commercial application. Herein, a single-crystal Ni-rich Li Ni_0.83Co_0.12Mn_0.05O₂ cathode material is synthesized and modified by a dual-substitution strategy in which ...     

Transition metal-free dearomatization of halonaphthols with C（sp3）-electrophiles

The first intermolecular electrophilic dearomatization of halonaphthols with benzyl/allyl bromides is described. Halonaphthols are used as carbon-nucleophiles in dearomatization to form three-dimensional cyclic enones with excellent chemoselectivity, in which etherification of phenolic hydroxyl group could be restrained well by using cesium carbonate as the base. A wide range of cyclic enones is directly prepared from various substituted benzyl/allyl bromides and halonaphthols. Mechanistic inves...     

Highly improved cyclic stability of Ni-rich/Li batteries with succinic anhydride as electrolyte additive and underlying mechanism

Lithium-metal battery based on Ni-rich cathode provides high energy density but presents poor cyclic stability due to the unstable electrode/electrolyte interfaces on both cathode and anode.In this work,we report a new strategy to address this issue.It is found that the cyclic stability of Ni-rich/Li battery can be significantly improved by using succinic anhydride(SA) as an electrolyte additive.Specifically,the capacity retention of LiNi_0.8Co_0.1Mn_0.1O₂     

Catalytic enantioselective synthesis of β-amino alcohols by nitrene insertion

Chiral β-amino alcohols are important building blocks for the synthesis of drugs, natural products, chiral auxiliaries, chiral ligands and chiral organocatalysts. The catalytic asymmetric β-amination of alcohols offers a direct strategy to access this class of molecules. Herein, we report a general intramolecular C(sp³)–H nitrene insertion method for the synthesis of chiral oxazolidin-2-ones as precursors of chiral β-amino alcohols. Specifically, the ring-closing C(sp³)–H amination of N-benzoyloxycarbamates with 2 mol% of a chiral ruthenium catalyst provides cyclic carbamates in up to 99% yield and with up to 99% ee.The method is applicable to benzylic, allylic, and propargylic C–H bonds and can even be applied to completely non-activated C(sp³)–H bonds, although with somewhat reduced yields and stereoselectivities. The obtained cyclic carbamates can subsequently be hydrolyzed to obtain chiral β-amino alcohols. The method is very practical as the catalyst can be easily synthesized on a gram scale and can be recycled after the reaction for further use. The synthetic value of the new method is demonstrated with the asymmetric synthesis of a chiral oxazolidin-2-one as intermediate for the synthesis of the natural product aurantioclavine and chiral β-amino alcohols that are intermediates for the synthesis of chiral amino acids, indane-derived chiral Box-ligands, and the natural products dihydrohamacanthin A and dragmacidin A.     

SYNTHESIS OF SILICON MONOMERS AND OLIGOMERS CONTAINING CYCLOHEXYLENE RING

1,3-Bis(trichlorosilyl) cyclohexane was obtained by addition of HSiCl_3, to cyclohexadiene-1,3in the presence of H_2PtCl_6.6H_2O in isopropyl alcohol. The new compound was ethanolysed andmethylated to form di-methyl tetra-ethoxy disilyl, tri-methyl tri-ethoxy disilyl and terta-methyldi-ethoxy disilyl cyclohexanes. These di-to tetra-functional monomers were hydrolyzed by hydrochloric acid in ether. The di-functional monomer yielded cyclic dimer similar to octamethylcyclotetrasiloxane and the tri-functionalmonomer, a cyclic tetramer, while in the case of tetra-functional monomer a cyclic octamer wasobtained. These compounds have not been reported in literature.     

Hyperbranched polylysine: Synthesis,mechanism and preparation for NIR-absorbing gold nanoparticles

The hyperbranched polylysine fluoroborate was synthesized by NH₃BF₄-Lys NCA ROP in triethylamine at 15℃, during which the cyclic dimer mainly initiated ROP as the secondary initiating species. The hyperbranched polylysine can be used as a stabilizer to prepare the NIR-absorbing HPlys@Au NPs.     

Radical cation salts induced domino reaction of anilines with enol ethers:Synthesis of 1,2,3,4-tetrahydroquinoline derivatives

A domino reaction of anilines with cyclic and acyclic enol ethers induced by catalytic amounts of TBPA^·+（5 mol%） was investigated and a series of 2,4-disubstituted-1,2,3,4-tetrahydroquinolines were synthesized.Different from cyclic enol ethers, when acyclic enol ethers were used in the reaction,they serve as surrogates of acetaldehyde,producing a series of 2-methyl-4- anilino-1,2,3,4-tetrahydroquinolines.A single electron transfer mechanism was proposed to rationalize the products formation.     

A Facile Solid Phase Synthesis of 2—Alkylthio—4（1H）—quinolones

The resin-bound cyclic malonic acid ester 2 reacted with aryl isothiocyanate and alkyl halides to afford the key intermediate arylthioaminomethylene cyclic malonic ester resin 3.Subsequently,resin 3 proceeded thermal cyclizaiton giving the 2-alkylthio-4(1H)-quinolones in good yields and excellent purties.     

Cleavage of the Fe—Fe Bond of （Me2SiSiMe2） [η^5－C5H4Fe（CO）2]2 with Na／Hg and Molecular Structure of the Ring－Opened Complex

The reaction of the rifle cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe-Fe bond to afford his-sodium salt ( Me2SiSiMe2 ) [η^5-C5H4Fe(CO)2]2 (4). The latter was not isolated and was used directly to react with MeI, PhCH2Cl, CH3C(O)Cl, PhC(O)Cl,Cy3SnCl (Cy= cyclohexyl) or Ph3SnCl to afford corresponding ring-opened derivatives (Me2SiSiMe2) [η^5-C5H4Fe(CO)2]2 [5, R=Me; 6, R=PhCH2; 7, R=CH3C(O); 8, R=PhC(O); 9, R = Cy3Sn or 10, R = Ph3Sn ]. The crystal and molecular structures of 10 were determined by X-ray diffraction analysis. The molecule took the desired ant/ conformation around the Si-Si bond. The length of the Si--Si bond is 0.2343(3)nm, which is essentially identical to that in the cyclic structure of 1[0.2346(4) tun]. This result unambiguously demonstrates that the Si--Si bond in the cyclic structure of 1 is not subject to obvious strain.     

Catalytic oxidation of cyclohexene to cyclohexanone by a triple system in acidic aqueous acetonitrile medium

The catalytic oxidation of cyclohexene to cyclohexanone using Pd(OAc)2/HQ/FePc was investigated in an acidic aqueous solution of acetonitrile. The role of each component of this system in the oxidation of cyclohexene was explored by means of UV-VIS, IR, XPS spectroscopy and cyclic voltammetry, respectively. Based on the experimental results, the mechanism of the oxidation of cyelohexene catalyzed by Pd(OAc)2/HQ/FePc was elucidated.     

In-situ construction of conducting alloy interphase towards modulating Li-ion storage kinetics

Interface engineering strategy shows great promise in promoting the reaction kinetic and cycling performance in the field of electrochemical energy storage application.In this work,an in-situ interface growth strategy is proposed to introduce a robust and conducting MoGe₂ alloy interphase between the electrochemical active Ge nanoparticle and flexible MoS₂ nanosheets to modulate their Li-ion storage kinetics.The structural evolution processes of the Ge@MoGe₂@MoS₂ composite are unraveled,during which the initially-generated Ge metals serve as a crucial reduction mediator in the formation of MoGe₂ species bridging the Ge and MoS₂.The as-generated MoGe₂ interface,chemically bonding with both Ge and MoS₂,possesses multi-fold merits,including the maintaining stable framework of electrochemically inactive Mo matrix to buffer the strain-stress effect and the"welding spot"effects to facilitate the efficient Li⁺/e^-conduction.As well,the introduction of MoGe₂ interface leads to a unique sequential lithiation/de^-lithiation process,namely in the order of the electrochemically active MoS₂-MoGe₂-Ge during lithiation and vice versa,during which the electrode strain could be more effectively released.Benefited from the robust and rigid MoGe₂ interface,the delicately designed Ge@MoGe₂@MoS₂ composite exhibits an improved charge/discharge performances(866.7 mAh g^-1 at 5.0 A g^-1 and 838.5 mAh g^-1 after 400 cycles)while showing a high tap density of 1.23 g cm^-3.The as-proposed in-situ interface growth strategy paves a new avenue for designing novel high-performance electrochemical energy storage materials.     

Electrochemical Dicarboxylation of Styrene： Synthesis of 2-Phenylsuccinic Acid

Electrochemical dicarboxylation of styrene in the presence of atmospheric pressure of CO2 with a Ti cathode and a Mg rod anode readily took place efficiently in an acetonitrile solution containing 0.1 mol·L^-1 tetraethylammonium bromide to give 2-phenylsuccinic acid. Influences of the nature of the electrodes, the current density, the passed charge and the temperature on electrolysis were studied to optimize the electrolytic conditions, with the maximal isolated yield to be 86.07%. The mechanism of the elelctrocarboxylation process has been studied by cyclic voltammetry.     

Coral reef-like polyanaline nanotubes prepared by a reactive template of manganese oxide for supercapacitor electrode

Coral reef-like PANI nanotubes composed of nanopaticles were successfully synthesized by a reactive template of manganese oxide.The structure was characterized by using SEM,TEM,and FT-IR,and the supercapacitive behaviors of these nanotubes were investigated with cyclic voltammetry（CV）,and charge-discharge tests,respectively.A maximum specific capacitance of 533 F/g could be achieved in 1mol/L aqueous H₂SO₄ with the potential range of -0.2 to 0.8 V（vs.the saturated calomel electrode） in a half-cell setup configuration for PANI electrode,suggesting its potential application in the electrode material for electrochemical capacitors.     

PREPARATION OF POLYMER—SUPPORTED RCpCpTiCl2 AND APPLICATION IN CATALYTIC ISOMERIZATION OF 1,5—HEXADIENE

Polymer-supported RCpCpTiCl2(Cp=η^5-C5H4;RCp=η^5-RC5H4)have been prepared and reduced by i-C3H7MgBr in situ，then used in catalytic isomerization of 1,5-hexadiene.The isomerization of 1,5-hexadiene leads to a mixture of cyclic and linear products.The ratio of cyclic to linear product depends on the nature of the supporter and the substituent on the cyclopentadienyl ring.The former contributes the most,for example,silica supported Cp2 TiCl2 gave cyclic-linear ratio of 99/1,while for polymer-supported Cp2TiCl2 species,linear compounds are the major products and the ratio of cyclic to linear product changes with different R groups on the cyclopentadienyl ring.