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81.
Enantioselective Generation of Adjacent Stereocenters in a Copper‐Catalyzed Three‐Component Coupling of Imines,Allenes, and Diboranes 下载免费PDF全文
Kay Yeung Rebecca E. Ruscoe Dr. James Rae Dr. Alexander P. Pulis Prof. Dr. David J. Procter 《Angewandte Chemie (International ed. in English)》2016,55(39):11912-11916
A highly enantio‐ and diastereoselective copper‐catalyzed three‐component coupling affords the first general synthesis of homoallylic amines bearing adjacent stereocenters from achiral starting materials. The method utilizes a commercially available NHC ligand and copper source, operates at ambient temperature, couples readily available simple imines, allenes, and diboranes, and yields high‐value homoallylic amines that exhibit versatile amino, alkenyl, and boryl units. 相似文献
82.
(PPh4)2[MoN(N3)3Cl]2; Synthesis, IR Spectrum, and Crystal Structure The title compound is formed in the reaction of molybdenum (II) benzoate with trimethylsilyl azide and PPh4Cl in dichloro methane forming dark red single crystals. A PPh3Me⊕ salt of the ion [MoN(N3)3Cl]22? is obtained from (PPh3Me)2MoNCl4] treated with silver azide in CH2Cl2 suspension. The solvent CH2Cl2 participates in both reactions as oxidizing agent. (PPh4)2[MoN(N3)3Cl2 is characterized by a structural analysis based upon X-ray data: space group P1 , Z = 1, a = 1050.7 pm; b = 1185.4 pm; c = 1190.8 pm; α = 98.90°; β = 106.87°; γ = 103.97° (4505 independent, observed reflexions, R = 0.039). The compound consists of PPh4⊕ cations and centrosymmetric anions [MoN(N3)3Cl22? in which the molybdenum atoms are bridged by the Nα atoms of two azide groups; the resulting Mo? N bond lengths are 208 pm and 260 pm. In trans position to the long Mo? N bond the terminal nitrido ligand is situated, the Mo?N distance of 164 pm corresponds to a triple bond. Two terminal azido ligands and the chloro ligand are filling up the coordination sphere of the molybdenum atoms to a coordination number of six. The i.r. spectrum is reported and assigned. 相似文献
83.
In this study, synthesis of poly(epichlorohydrin-g-methyl methacrylate) graft copolymers by reversible addition-fragmentation chain transfer (RAFT) polymerization was reported. For this purpose, epichlorohydrin was polymerized by using HNO3 via cationic ring-opening mechanism. A RAFT macroinitiator (macro-RAFT agent) was obtained by the reaction of potassium ethyl xanthogenate and polyepichlorohydrin. The graft copolymers were synthesized using macro-RAFT agent as initiator and methyl methacrylate as monomer. The synthesis of graft copolymers was conducted by changing the time of polymerization and the amount of monomer-initiator concentration that affect the RAFT polymerization. The effects of these parameters on polymerization were evaluated via various analyses. The characterization of the products was determined using 1H-nuclear magnetic resonance (1H-NMR), Fourier-transform infrared spectroscopy, gel-permeation chromatography, thermogravimetric analysis, elemental analysis, and fractional precipitation techniques. The block lengths of the graft copolymers were calculated by using 1H-NMR spectrum. It was observed that the block length could be altered by varying the monomer and initiator concentrations. 相似文献
84.
Cheremina O Bachmakov I Neubert A Brune K Fromm MF Hinz B 《Biomedical chromatography : BMC》2005,19(10):777-782
Oxycodone (14-hydroxy-7,8-dihydrocodeinone) is a potent opioid receptor agonist. In the present study, a liquid-liquid extraction-based reversed-phase HPLC method with UV detection was validated and applied for the analysis of oxycodone and its major metabolite, noroxycodone, in human plasma. The analytes were separated using a mobile phase, consisting of acetonitrile and phosphate buffer (8:92, v/v) at a flow rate of 1 mL/min, and UV detection at 205 nm. The retention times for oxycodone, noroxycodone and codein (internal standard) were 14.7, 13.8 and 10.2 min, respectively. The validated quantitation range of the method was 2-100 ng/mL for oxycodone and 10-100 ng/mL for noroxycodone. The developed procedure was applied to assess the pharmacokinetics of oxycodone and its metabolite following administration of a single 20 mg oral dose of oxycodone hydrochloride to one healthy male volunteer. 相似文献
85.
Transference numbers are reported for LiCl and NaCl in methanol at 25°C and for NaCl, KCl, and Bu4NBr in methanol at 10°C. The potentiometric moving-boundary method as developed by Kay and Fratiello was employed to give a precision of about 0.05% and an accuracy of at least 0.1% as indicated by two independent determinations of the conductances of the Cl– and Br– ions. The data are extrapolated by the Fuoss-Onsager theory, and the magnitude of the electrophoretic effect is calculated as described by Kay and Dye. The agreement with this theory is quite good at both temperatures, although the å value required in the case of Bu4NBr is considerably larger than that obtained from conductance data. This agreement contrasts with that obtained for ethanol and acetone solutions where the measured electrophoretic effect is considerably larger than the corresponding calculated values. The importance of this fact in the determination of ion-pair association constants is discussed. 相似文献
86.
Inhomogeneous broadening of resonance lines causes a reduction of absorption in nuclear resonance experiments. This is particularly devastating to the observation of the Mössbauer effect in isomers like 107Ag with a half-life of 44s.It has been suggested in the literature that homogeneous broadening can provide overlap of resonance lines and thus theMössbauer effect can be recovered. The analysis presented in this paper shows that this is not the case for Mössbauer experiments, unless the radiative width ΓΓ also increases. Although overlap occurs when the lines are homogeneously broadened to a total width Γ_H which exceeds the natural width Γ, and the inhomogeneous width Δ, the Mössbauer absorption remains low because it is proportional to the factor of Γγ/Γ H. 相似文献
87.
Graeme J. Gainsford M. Delower H. Bhuiyan Andrew J. Kay 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(4):o195-o198
The compounds N‐[2‐(4‐cyano‐5‐dicyanomethylene‐2,2‐dimethyl‐2,5‐dihydrofuran‐3‐yl)vinyl]‐N‐phenylacetamide, C20H16N4O2,(I), and 2‐{3‐cyano‐5,5‐dimethyl‐4‐[2‐(piperidin‐1‐yl)vinyl]‐2,5‐dihydrofuran‐2‐ylidene}malononitrile 0.376‐hydrate, C17H18N4O·0.376H2O, (II), are novel push–pull molecules. The significant bonding changes in the polyene chain compared with the parent molecule 2‐dicyanomethylene‐4,5,5‐trimethyl‐2,5‐dihyrofuran‐3‐carbonitrile are consistent with the relative electron‐donating properties of the acetanilido and piperidine groups. The packing of (I) utilizes one phenyl–cyano C—H...N and two phenyl–carbonyl C—H...O hydrogen bonds. Compound (II) crystallizes with a partial water molecule (0.376H2O), consistent with cell packing that is dominated by attractive C—H...N(cyano) interactions. These compounds are precursors to novel nonlinear optical chromophores, studied to assess the impact of donor strength and the extent of conjugation on bond‐length alternation, crystal packing and aggregation. 相似文献
88.
Cryogenic CO2 formation on oxidized gold clusters synthesized via reactive layer assisted deposition
Gas-phase Au atoms deposited onto a multilayer film of molecular oxygen produce atomic oxygen bound to gold clusters. After removal of molecular O2, temperature programmed desorption and molecular beam techniques show that the atomic oxygen readily reacts with CO to produce CO2. At present, the structure and size distribution of these clusters are unknown. Nevertheless, CO2 forms on these clusters upon exposure to CO at temperatures as low as 35 K. Furthermore, above 120 K, the reaction goes to completion with initial reaction yields as high as 50%. 相似文献
89.
Severin K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(7):1515-1519
Several methods to synthesize bimetallic complexes in which two different metal fragments are connected by halide bridges are described. Using simple starting materials a large pool of structurally defined bimetallic complexes with unique chemical reactivities can be prepared in short time. Applications in organometallic synthesis and homogeneous catalysis are discussed. 相似文献
90.