Constituents from Rubia Ustulata Diels and R. Yunnanensis Diels and Their Antiplatelet Aggregation Activity

A new anthraquinone glycoside, rubiayannone‐A ( 1 ), and a new coumarin, rubilatin‐A ( 2 ), together with twenty‐two known compounds were isolated and characterized from the roots of Rubia ustulata. A new anthraquinone, 2‐carbomethoxyanthraquinone ( 3 ), and rubiayannone‐A, 2‐formylanthraquinone were obtained from the roots of R. yunnanensis. The structures of those compounds were elucidated by spectroscopic methods. The antiplatelet aggregation activity of the isolated compounds 1, 4～6 were also discussed.     

A dimeric constrained‐geometry titanium complex linked by double Ti–CH2–Al–CH2 heterocycles

In the structure of bis({N‐[di­methyl(1η⁵‐2,3,4,6‐tetra­methyl­in­den­yl)­silyl]­cyclo­hexyl­amido‐1κN}(methyl‐3κC)‐di‐μ₃‐methyl­ene‐1:2:3κ³C;1:3:3′κ³C‐tris(pentafluorophenyl‐2κC)titanium) benzene disolvate, [Me₂Si(η⁵‐2,3,4,6‐Me₄C₉H₂)(C₆H₁₁N)]Ti[(μ₃‐CH₂)Al(C₆F₅)₃][AlMe(μ₃‐CH₂)]₂ or [Ti₂(C₂₁H₇AlF₁₅)₂(C₂₁H₃₁NSi)₂]·2C₆D₆, the dimer is located on an inversion center, and the two Ti centers are linked by double Ti(μ₃‐CH₂)Al(C₆F₅)₃AlMe(μ₃‐CH₂) heterocycles. The electron‐deficient Ti centers are further stabilized by two α‐agostic interactions between Ti and one H atom of each bridging methyl­ene group.     

Kinetic study of triphenylphosphine addition to para‐benzoquinone

Kinetics of the addition reaction of triphenylphosphine to para‐benzoquinone in 1,2‐dichloroethane as solvent was studied. Initial rate method was used to determine the order of the reaction with respect to the reactants. Pseudo‐first‐order method was also used to calculate the rate constant. This reaction was monitored by UV‐vis spectrophotometry at 520 nm by variable time method. On the basis of the obtained results, the Arrhenius equation of this reaction was obtained: The activation parameters, E_a, ΔH^#, ΔG^#, and ΔS^# at 300 K were 5.701, 6.294, 19.958 kcal mol^?1 and ?45.853 cal mol^?1 K^?1, respectively. This reaction is first and second order with respect to triphenylphosphine and para‐benzoquinone, respectively. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:472–479, 2004     

含轴手性磺酸配体的镉配合物(英)

The crystal structure of [Cd(BDA)(phen)₂(H₂O)](H₂O)₂ (1) (BDA=6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate, phen=1,10-phenanthroline)consists of a cadmium center whose coordination environment can be best described as a slightly distorted octahedron defined four nitrogen atoms from two phen ligands and two oxygen atoms differently from BDA ligand and water. There are strong hydrogen-bonding interactions between water and sulfonate group of BDA ligands to construct the 3D network. CCDC: 277921.     

Electrocatalytic Oxidation of Dopamine by Ferrocene in Lipid Film Cast on a Glassy Carbon Electrode

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Four‐ and Five‐Coordinate Gallium Complexes Stabilized by Bidentate 2‐(Dimethylaminomethyl)Pyrrole Ligand: Molecular Structures of Ga[NC4H3(CH2NMe2)‐2]3 and GaMe2[NC4H3(CH2NMe2)‐2]

Treatment of GaCl₃ with one equiv of Li[NC₄H₃(CH₂NMe₂)‐2] (n = 1, 2, 3) in diethyl ether at ?78 °C yields GaCl_3‐n[NC₄H₃(CH₂NMe₂)‐2]_n (n = 1, 1 ; n = 2, 2 ; n = 3, 3 ). Compound 1 reacts with two equiv of RLi to afford GaR₂[NC₄H₃(CH₂NMe₂)‐2] ( 4a, R=Me; 4b, R=Bu ) via transmetallation. Reacting 2 with one equiv of RLi in diethyl ether, 3 and 4 are formed via ligand redistribution. Variable temperature ¹H NMR spectroscopic experiments reveal that the five‐coordinate gallium compound 3 is fluxional and results in a coalescence temperature at 5 °C, at which ΔG^≠ is calculated at ca. 10.4 Kcal/mole. All the new compounds have been characterized by ¹H and ¹³C NMR spectroscopy and the structures of compounds 3 and 4a have also been determined by X‐ray crystallography.     

Three New Triterpenoids from Lycopodium japonicum Thunb

Three new triterpenoids, (3β,8β,14α,21α)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 1 ), (3β,8β,14α,21β)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 2 ), and lycopodiin A ( 3 ), together with four known compounds, lycoclavanol ( 4 ), lycoclaninol ( 5 ), α‐onocerin ( 6 ), and 3‐epilycoclavanol ( 7 ), were isolated from Lycopodium japonicum Thunb (Lycopodiaceae). Their structures were established by means of spectroscopic analyses. Compounds 3 and 7 showed moderate antitumor activity. Compounds 4 and 6 exhibited acetylcholinesterase inhibition activity.     

New Dammarane Monodesmosides from the Acidic Deglycosylation of Notoginseng‐Leaf Saponins

Three new dammarane monodesmosides, named notoginsenosides Ft₁ ( 1 ), Ft₂ ( 2 ), and Ft₃ ( 3 ), together with three known ginsenosides, were obtained from a mild acidic hydrolysis of the saponins from notoginseng (Panax notoginseng (Burk .) F. H. Chen ) leaves. Their structures were elucidated to be (3β,12β,20R)‐12,20‐dihydroxydammar‐24‐en‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 1 ), (3β,12β)‐12,20,25‐trihydroxydammaran‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 2 ), and (3β,12β,24ξ)‐12,20,24‐trihydroxydammar‐25‐en‐3‐yl O‐β‐D ‐xylopyranosyl‐(1 → 2)‐O‐β‐D ‐glucopyranosyl‐(1 → 2)‐β‐D ‐glucopyranoside ( 3 ), by means of spectroscopic evidences. The known ginsenosides Rh₂ and Rg₃ 4 – 6 were obtained as the major products from this acidic deglycosylation.     

Promotion of Ionic Liquid to Dimethyl Carbonate Synthesis from Methanol and Carbcn Dioxide

Promotion of ionic liquid, 1-ethyl-3-methylimidazolium bromide (emimBr), to the synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in the presence of potassium carbonate and less amount of methyl iodide under mild conditions was investigated. The results showed that the high selectivity and raised yield of DMC was achieved due to the addition of emimBr in the reaction system. And effect of several reaction conditions such as temperature, pressure and amount of emimBr was discussed.     

Enhanced thermal properties and flame retardancy from a thermosetting blend of a phosphorus‐containing bismaleimide and epoxy resins

Epoxy resins modified by an organosoluble phosphorus‐containing bismaleimide (3,3′‐bis(maleimidophenyl) ­phenylphosphine oxide; BMPPPO) were prepared by simultaneously curing epoxy/diaminodiphenylmethane (DDM), and BMPPPO. The resulted epoxy resins were found to exhibit glass transition temperatures as high as 212 °C, thermal stability at temperatures over 350 °C, and excellent flame retardancy with Limited oxygen index (LOI) values around 40. Incorporation of BMPPPO into epoxy resins via the thermosetting blend was demonstrated to be an effective way to enhance the thermal properties and flame retardancy simultaneously. Copyright © 2003 John Wiley & Sons, Ltd.