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101.
Synthesis of C-3' methyl taxotere (docetaxel) 总被引:1,自引:0,他引:1
Protected (3R,4S)-N-Boc-3-hydroxy-4-methyl-4-phenylazetidin-2-one has been synthesized stereoselectively and used to esterify protected 10-desacetylbaccatin III to give, following removal of the protecting groups, novel C-3' methyl taxotere (docetaxel). 相似文献
102.
Eric Monflier Sbastien Tilloy Georges Fremy Yves Castanet Andr Mortreux 《Tetrahedron letters》1995,36(52):9481-9484
Solvent free biphasic hydroformylalion of various water-insoluble terminal olefins can be achieved in high yields and sclcctivitics by using a water-soluble rhodium/triphenylphosphine trisulfonate catalyst and per(2,6-di-o-mclhyl)-β-cyclodcxtrin as inverse phase transfer catalyst. The catalytic activities were up to ten times higher than those observed without pcr(2,6-di-o-methyl)-β-cyclodextrin. 相似文献
103.
Further studies on dppm-stabilized mixed-metal clusters: X-ray structure of PdPtCoCl(CO)3(μ-dppm)2
1
Pierre Braunstein Claude de Bellefon Yves Dusausoy Daniel Bayeul 《Journal of Cluster Science》1995,6(1):175-185
The metalloligated mixed-metal cluster [PdPtCo2(CO)7(-dppm)2] (2) (dppm = -Ph2PCH2PPh2) possesses numerous potential reaction centers (e.g., metal(s), metal-metal bonds, CO, and dppm ligands) and this has previously led to an investigation of the site selectivity of reactions with nucleophiles. The exocyclic CO(CO)4 fragment was substituted with a chloride ligand and the resulting chiral, triangular cluster PdPtCoCl(CO)3(-dppm)2 (4) has been structurally characterized. The Pd-Co and Pt-Co edges of this almost equilateral triangle are bridged by a dppm ligand, and two of the three carbonyls borne by the Co atom are semi-triply bridging above and below the plane of the metals. The Co(CO)3P fragment behaves as an anionic 4-electron donor organometallic bridging group toward thed
9-d
9 Pd(I)-Pt(I) unit. Crystal data for4, monoclinic space groupP21/n with Z=4 in a unit cell of dimensionsa=12.291(3),b=19.321(4),c=23.680(5) Å,=100.05(2)°. The structure has been solved from diffractometer data by Patterson, Fourier methods and refined by full-matrix least squares on the basis of 3512 observed reflections (l>3) toR(F) andR
w(F) values of 0.059 and 0.061.Dedicated to Professor L. F. Dahl on the occasion of his 65th birthday, with our sincere congratulations and best wishes. 相似文献
104.
Sergei V. Levchik Giovanni Camino Maria Paola Luda Luigi Costa Bruno Costes Yves Henry Emile Morel George Muller 《先进技术聚合物》1995,6(2):53-62
Tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) undergoes homopolymerization on heating. Intramolecular reactions which compete with crosslinking favor the formation of cyclic structures with increasing thermal and fire resistance of the resin, whereas physical mechanical properties tend to decrease. The mechanism of thermal decomposition of TGDDM is studied by thermogravimetry, differential scanning calorimetry and thermal volatilization analysis with characterization of volatiles evolved and residue left. Thermal degradation of poly-(TGDDM) starts at 260°C with elimination of water from secondary alcoholic groups which is a typical pathway for epoxy resin degradation. Resulting unsaturations weaken bonds in the β-position and provoke the first chain breaking at allyl–amine and allyl–either bonds. With increasing temperature, saturated alkyl–ether bonds and alkyl carbon–carbon bonds are broken first, followed by the most stable alkyl–aryl bonds at T>365°C. The combustion performance of TGDDM is discussed on the basis of the thermal degradation behavior. 相似文献
105.
Grancher D Jaussaud P Durix A Berthod A Fenet B Moulard Y Bonnaire Y Bony S 《Journal of chromatography. A》2004,1059(1-2):73-81
This paper describes a new method of purification of the Lolitrem B, a tremorgenic mycotoxin produced in planta by the endophytic fungus Neotyphodium lolii. The method is based on the large-scale isolation of the toxin by countercurrent chromatography (CCC). The lolitrem B content in endophyted ryegrass seed, 11 microg/g or 11 ppm, is extracted by stirring finely ground seeds with ethanol for 3 h at room temperature. The concentrated crude extract contains about 0.6 mg/g or 600 ppm of lolitrem B. It is then submitted to CCC purification with a biphasic four-solvent liquid system. A 160-fold enrichment was obtained in one step producing a raffinate containing 10% or 100 mg/g of the toxin. Further purifications were then performed by thin layer and low pressure liquid chromatography. Twenty-eight micrograms of lolitrem B with a 96% purity grade were obtained from 8 kg of seeds (yield 32%). 相似文献
106.
The 2-Phenyl-4,5-dimethylphosphorin P-W(CO)5 complex reacts easily as a dienophile with 2,3-dimethylbutadiene through its 1,6-positions and as a diene with N-phenylmaleimide, dimethyl acetylenedicarboxylate and cyclopentadiene, through its 1,4-positions. 相似文献
107.
The reactivity of (diethoxy)-N-methyl-N-benzyl phosphoramide (I) and bis(dinethylamino)-N-methyl-N-benzylphosphoramide (II) when treated with strong bases (RLi, R2NLi) is very different: (I) gives a novel elimination, whereas (II) under the same experimental conditions gives a stable carbanion whose reactivity has been investigated. 相似文献
108.
Fernando J. S. Oliveira Francisca P. De França 《Applied biochemistry and biotechnology》2005,122(1-3):593-603
A 23 full factorial experimental design was adopted to estimate the effects of three variables on the biodegradation of oil during
soil bioremediation: bioaugmentation seeding a mixed culture, addition of fertilizer or mineral media, and correction of initial
pH of the soil to 7.0. The tests were carried out in polyvinyl chloride reactors with 5.0 kg of crude oil-contaminated soil
at 14 g/kg. After screening the variables, soil bioremediation tests were conduced with varied C:N ratios, yielding an increase
in biodegradation of the oil heavy fraction from 24 to 65%, consumption of total n-paraffins, and a remarkable decrease in the concentration of residual polycyclic aromatic hydrocarbons of the soil. 相似文献
109.
L De Boni L T Fran?a H P Grieneisen M Janowicz T B Kist A R Consiglio J R Schoffen V Stefani C Termignoni 《Electrophoresis》1999,20(12):2493-2500
The phenomenon of electrophoresis in free solution has been studied theoretically down to the molecular level for decades. In addition, intermolecular photo-induced proton transfer reactions, which occur in a wide class of molecules (phenols and aminoarenes) as well as proteins (green fluorescent protein), were also studied extensively. However, the study of the effect of light-induced electrophoretic mobility changes of the analytes in electrophoresis was begun only recently. In the present work, capillary zone electrophoresis was chosen as the environment to measure the magnitude of these electrophoretic mobility shifts induced by light. Background electrolytes (running electrolytes) with high refractive indices were developed, allowing the capillary to work like an optical fiber. The experimental conditions for obtaining stable coupling and guided laser light along the liquid core are discussed. Experimental evidence of band compression is observed, leading to a solitary wave behavior of the analyte band (2-naphthol). These solitary waves result from competition between thermal diffusion (dispersion mechanism) and a nonlinear (band compression) effect due to the combined electrophoresis phenomenon and absorption of guided light by the molecules of the band (which are subjected to a "reversible intermolecular proton transfer reaction" as one of their decay routes). The possibilities of applying this effect to different methods and techniques are also discussed. 相似文献
110.
The use of an in situ generated Ni(0) catalyst associated with 2,2'-bipyridine or N,N'-bis(2,6-diisopropylphenyl)dihydroimidazol-2-ylidene (SIPr) as a ligand and NaO-t-Bu as the base for the intramolecular coupling of aryl chlorides with amines is described. The procedure has been applied to the formation of five-, six-, and seven-membered rings. [reaction: see text] 相似文献