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991.
Optically active 1, 2-Diphenylethylendiamine(9) is obtained by asymmetric oxidative coupling reaction of d-camphor ketimine anion (4). Among various oxidating agents, TiCl(Oipr)3 is better than l2, Br2, CuCl2, FeCl3 and BrCH2CH2Br. 相似文献
992.
Oxidative coupling reactions of N,N‐dialkylanilines with cerium(IV) ammonium nitrate can be achieved by grinding at room temperature in the absence of solvents. 相似文献
993.
A mild, simple, and efficient synthetic procedure for the preparation of 2-monobromo-, 2,7-dibromo-, and 2,2′,7,7′-tetrabromo-substituted spirobifluorene derivatives and their key intermediates, 2-monobromo- and 2,7-dibromo-substituted fluorene compounds, has been developed. The oxidative bromination of fluorene and spirobifluorene was achieved using NaBr/H2O2 as the bromine source. High conversion of the starting materials was achieved together with good selectivities under optimized reaction conditions. 相似文献
994.
Catalytic asymmetric Reformatsky reactions of benzaldehyde with optically active menthyl bromoacetates in the presence of Zn-Cu couple were performed using 0.25 equiv. of (1R,2S) or (1S,2R)-dimethyl-2-amino-1,2-diphenyl ethanol as chiral ligand to obtain β - hydroxy esters with enantioselectivities up to 60.2%. The obvious double chiral induction effect was observed while chiral ligands matched with optically active substrates. 相似文献
995.
A series of cholesterylated thiogalactosides L1 –L6 the cell targeting ligands for gene delivery to hepatocytes, was synthesized. Related poly(ethylene glycol) chain was used as a bridge for the attachment of galactoside on one hydroxyl end, while the other hydroxyl end was linked with cholesterol. This design provided an effective entry for the synthesis of a poly(ethylene glycol) compound with the hepatocyte targeting. 相似文献
996.
An efficient and facile method has been developed for the condensation of 1,2-diamines with α-hydroxyketones in polyethylene glycol (PEG) to quinoxalines and pyrazines with good yields in the presence of silica sulfuric acid (SSA). The important features of the methodology are simple operations, environmentally friendliness, and no requirement for metal catalysts. Additionally, the catalyst system (SSA/PEG) could be recovered easily and reused. 相似文献
997.
998.
Yu Li Bijaya Thapa Hua Zhang Xuefei Li Fanghua Yu Eun-Kee Jeong Zhigang Yang Zhong-Xing Jiang 《Tetrahedron》2013
A family of fluorinated gemini surfactants derived from perfluoropinacol has been synthesized as novel 19F magnetic resonance imaging (19F MRI) agents. These fluorinated surfactants with 12 symmetric fluorine atoms and one singlet 19F MR peak can be conveniently prepared from perfluoropinacol and oligo(ethylene glycols) on multi-gram scales. Solubility, hydrophilicity (log P), and critical micelle concentration (CMC) measurements of these fluorinated surfactants indicated that high aqueous solubility can be achieved by introducing oligo(ethylene glycols) with appropriate length into perfluoropinacol, i.e., manipulating the fluorine content (F%). One of these fluorinated surfactants with high aqueous solubility and excellent 19F MR properties has been identified by 19F MRI phantom experiments as a promising 19F MRI agent. 相似文献
999.
A direct transformation from methyl ketones to secondary or tertiary amides has been developed through a novel electrochemical approach and a wide scope of formamides could be utilized as the amide sources. This transformation was promoted by in situ generated iodine through electrolysis of sodium iodide under mild, metal-free conditions. This electrochemical procedure could avoid the use of stoichiometric iodine and afforded the target products in good to excellent yields. 相似文献
1000.
A series of heterometallic LnIII–SbIII edta‐containing compounds with the formulas [Sb2(edta)2Ln]NO3 · nH2O [edta = ethylenediaminetetraacetate; Ln = Eu, n = 7 ( 1 ); Gd, n = 7.5 ( 2 ) and Tb, n = 8 ( 3 )] were synthesized and characterized by elemental analyses (EA), powder X‐ray diffraction (PXDP), Fourier transform infrared spectroscopy (FT‐IR), and thermogravimetric analyses (TGA). Their fluorescence and magnetic properties were also studied. The thermal analysis demonstrates the compounds formation of the antimony, lanthanide ions, and edta4– ligands. FT‐IR spectra reveal that the antimony and lanthanide ions are connected through the carboxylate bridges. The studies of luminescence properties show that compounds 1 and 3 exhibit typical luminescence in the visible region. Furthermore, magnetic properties reveal compounds 2 and 3 have weak ferromagnetic behavior. 相似文献