Easily accessible chiral dicyclopentadiene ligands for rhodium-catalyzed enantioselective 1,4-addition reactions

A variety of novel C₁-symmetric chiral diene ligands based on the dicyclopentadiene (DCP) skeleton were easily prepared from commercially available DCP. The application of these diene ligands in the rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds has been examined and excellent enantioselectivities (up to 97% ee) as well as good yields were achieved under mild reaction conditions.     

Synthesis of new acetal aza-cage compounds via ozonolysis of bis-endo-diol- and diacylnorbornene derivatives

We synthesized acetal aza-cage compounds directly via ozonolysis of 2,3-bis-endo-diol- and diacylnorbornenes in dichloromethane at ?78 °C. Ozonolysis of the diols followed by addition of amines gave the aza-cage compounds in high yields. The reaction mechanism for the formation of this type of aza-cage compounds is proposed to proceed via the hydroperoxide intermediate. Ozonolysis of the diacetyl norbornene followed by addition of (1) primary amines gave monoaza-cages and diaza-cage, (2) tert-butylamine gave hydroxyl lactone and diaza-cages, and (3) amino acid ester gave optically active aza-cages, in which one compound was converted into chiral aminoalcohol and structure of another was proven by X-ray analysis. A mechanism via the final ozonide and the imine intermediates is proposed for the formation of this type of aza-cages.     

(N,N-Diisopropylcarbamoyloxy)-methyl p-tolyl sulfone: preparation and application for the syntheses of 1,2-diols

1-(N,N-Diisopropylcarbamoyloxy)-1-tosyl-methane (CbOCH₂Ts, Cb=N,N-diisopropylcarbamoyl) was readily prepared from p-TolSH, paraformaldehyde and CbCl. With the dual activation of CbO- and Ts-substitutions, deprotonation of CbOCH₂Ts could be effected not only by n-BuLi, but also by Grignard reagents. Upon deprotonation, the title compound adds to various carbonyl structures. By choosing proper organometallic reagents for consecutive steps, the addition intermediate undergoes in situ conversions to efficiently yield regioselectively O-Cb protected and unprotected 1,2-diols.     

Briarenolide E: the first 2-ketobriarane diterpenoid from an octocoral Briareum sp. (Briareidae)

A novel 2-ketobriarane diterpenoid, briarenolide E (1), was isolated from an octocoral Briareum sp. The structure of briarane 1 was elucidated by interpretations of spectral data. Compound 1 displayed modestly inhibitory effects on the generation of superoxide anions and the release of elastase by human neutrophils.     

Improving the softness of BOPP films: From laboratory investigation to industrial processing

Young's modulus of biaxially oriented polypropylene (BOPP) films prepared with homemade film stretcher was investigated,which can be used to indicate the softness of fihns.It was found that the modulus of films was decreased by about 69％ as the content of polyethylene (PE) added into polypropylene (PP) reached 30％.Also,increasing draw temperature can induce lower stress level during stretching,which may lead to the formation of crystals with low orientation level and thus decreased modulus of films.Based on laboratory study,BOPP films produced on commercial line were studied by differential scanning calorimetry (DSC),wide and small-angle X-ray scattering (WAXS,SAXS) with varying contents of PE.SAXS results show that the crystals are oriented in both machine direction (MD) and transverse direction (TD),and the crystals are more oriented in TD than MD according to the WAXS results for all films.Also,the orientation parameter of crystal along TD increases from 0.68 to 0.83 as the contents of PE increase from 0％ to 25％.Meanwhile,the modulus of films in MD declines with increase of PE contents generally,improving the film softness.Orientation of crystals is thus an effective structure parameter to adjust the film softness.The relationship of processing-structure-property is also established.     

Eosin Y as a Direct Hydrogen‐Atom Transfer Photocatalyst for the Functionalization of C−H Bonds

Eosin Y, a well‐known economical alternative to metal catalysts in visible‐light‐driven single‐electron transfer‐based organic transformations, can behave as an effective direct hydrogen‐atom transfer catalyst for C?H activation. Using the alkylation of C?H bonds with electron‐deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y‐based photocatalytic hydrogen‐atom transfer strategy is promising for diverse functionalization of a wide range of native C?H bonds in a green and sustainable manner.     

Tuning the morphology of amphiphilic copolymer aggregates by compound emulsifier via emulsion–solvent evaporation

A series of poly(4-vinylpyridine)-b-poly{6-[4-(4-butyloxyphenylazo)phenoxy]hexyl methacrylate} (P4VP-b-PAzoMA) were employed to fabricate aggregates via the emulsion–solvent evaporation method. The emulsion was stabilized by compound emulsifier composed of SDS and span60. By tuning the ratio of two emulsifiers, P4VP-b-PAzoMA could self-assemble into various morphologies including porous microspheres, tremella-like aggregates, bowl-like aggregates and wrinkled microspheres. The transformation of the morphologies could be ascribed to three major aspects: the stability of emulsified chloroform droplets, the permeation of water into chloroform and the dispersity of the interior water droplets with regard to different HLB values. Besides, the morphology could even be tuned by changing the block ratio and the concentration of P4VP-b-PAzoMA, and the HLB dependent morphology changing was also proved within other block ratio or different concentration. The study uncovers a convenient and effective technique to manipulate the morphology of amphiphilic copolymer aggregates.     

Sensitive and Selective Determination of 2,4,6-Trichlorophenol Using a Molecularly Imprinted Polymer Based on Zinc Oxide Quantum Dots

Novel core-shell molecularly imprinted polymers were prepared based on zinc oxide quantum dots for the determination of 2,4,6-trichlorophenol by fluorescence. Principally, ZnO quantum dots and 2,4,6-trichlorophenol were chosen as the core substrate and the template molecule, respectively. The specific recognition sites for 2,4,6-trichlorophenol were obtained during the polymerization process in presence of 3-aminopropyltriethoxysilane and tetraethylorthosilicate. Molecularly imprinted ZnO quantum dots were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy and the optical properties were evaluated by spectrofluorometry. Under the optimal conditions, molecularly imprinted ZnO quantum dots were successfully applied to the sensitive determination and selective recognition of 2,4,6-trichlorophenol in water. A linear relationship was obtained to cover the concentration range of 0–160?µmol?L^?1 with a correlation coefficient of 0.9931 calculated by the Stern–Volmer equation. The products were used for the determination of 2,4,6-trichlorophenol in the water from local rural areas and the results strongly supported that the molecularly imprinted ZnO quantum dots were suitable for the determination of 2,4,6-trichlorophenol in real examples.     

Nano-crystalline FeOOH mixed with SWNT matrix as a superior anode material for lithium batteries

Nano-crystalline FeOOH particles(5～10 nm) have been uniformly mixed with electric matrix of single-walled carbon nanotubes(SWNTs)for forming FeOOH/SWNT composite via a facile ultrasonication method. Directly using the FeOOH/SWNT composite(containing 15 wt%SWNTs) as anode material for lithium battery enhances kinetics of the Li+insertion/extraction processes, thereby effectively improving reversible capacity and cycle performance, which delivers a high reversible capacity of 758 mAh g-1under a current density of 400 mA g-1even after 180 cycles, being comparable with previous reports in terms of electrochemical performance for FeOOH anode. The good electrochemical performance should be ascribed to the small particle size and nano-crystalline of FeOOH, as well as the good electronic conductivity of SWNT matrix.