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941.
A regioselective double 1,1‐hydrosilylation of terminal aliphatic alkynes with primary silanes catalyzed by one cobalt catalyst has been developed. gem‐Bis(dihydrosilyl)alkanes containing four silicon‐hydrogen bonds are efficiently constructed in an atom‐economical manner. Tolerated substrates include simplest alkyne‐ethyne, a complicated drug derivative and various functionalized terminal aliphatic alkynes. Asymmetric approach using two catalysts is achieved with excellent enantioselectivities to access corresponding chiral products. The transformations of Si—H bonds into Si—C, Si—O, and Si—F bonds and the synthesis of enantioriched α‐hydroxysilane show synthetic utility.  相似文献   
942.
A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed. The method exhibits a broad substrate scope for thiols, aryl iodides and amino acid units. Peptide macrocycles of a wide range of size and composition can be readily assembled in high yield from various easily accessible building blocks. This method has been successfully employed to prepare an 8-million-membered tetrameric cyclic peptide DNA-encoded library (DEL). Preliminary screening of the DEL library against protein p300 identified compounds with single digit micromolar inhibition activity.

A highly efficient and versatile method for construction of peptide macrocycles via palladium-catalyzed intramolecular S-arylation of alkyl and aryl thiols with aryl iodides under mild conditions is developed.  相似文献   
943.
The carboxyl group of a N-acylated amino acid may be protected by conversion to an oxazole derivative which, on photoxygenation, regenerates the carboxyl group in activated (triamide) form for peptide synthesis.  相似文献   
944.
An asymmetric hydrogenation of aroylacrylic acids catalyzed by RuPHOX-Ru catalyst has been developed, affording the corresponding chiral γ-lactones in high yields and with up to 93% ee. The methodology has the advantage of utilizing easily accessible substrates and has therefore expand the scope of the resulting chiral γ-lactones. Furthermore, high catalytic efficiency was achieved in that the reduction of both the CC and CO double bonds was achieved in one step. The current work provides an alternative and convenient pathway for the synthesis of a wide range of chiral γ-lactones.  相似文献   
945.
Epitaxial Prussian blue (PB) films are deposited electrochemically onto a Au(110) substrate. High-resolution X-ray diffraction shows that the PB films have a [111] out-of-plane orientation. The very large lattice mismatch of 148% is reduced to about 1% by the formation of (1 x 2)PB(111)[onemacr;10]//(6 x 5)Au(110)[onemacr;10] and (1 x 2)PB(111)[01onemacr;]//(6 x 5)Au(110)[onemacr;10] epitaxial relationships. Peaks in the cyclic voltammogram of PB on Au(110) are sharper than those on polycrystalline Au, consistent with higher structural order and a single out-of-plane orientation. The development of epitaxial films of PB and PB analogues will allow the measurement of the orientation-dependent properties of these molecular magnets. It will also open the door to the development of novel molecular spintronic devices, such as those which exhibit spin-dependent electron transfer.  相似文献   
946.
947.
Novel hexadecyl 3- { 4-[2-hydroxy-3(isopropylamino)propoxy]phenyl }propionate (HPP)was synthesized and its effect on delivery of liposomes into cultured cardiomyocytes was examined. The structure of HPP was characterized by IH NMR, 1R and MS. The amount of cardiomyocytes uptake of HPP-liposome was 3.9-fold higher than plain-liposome, and the increase was 6.2-fold when hypoxia happens. It indicated that HPP was a potential ligand for liposome targeting to ischemic myocardium.  相似文献   
948.
流动注射分析光度法同时测定镍和铁   总被引:7,自引:0,他引:7  
曲祥金  周杰 《分析化学》1997,25(2):168-171
建立了流动注射(FIA)光度法同时测定镍和铁的新方法,以乙酸-乙酸钠缓冲溶液(PH4.50)作载液,溴化十六烷基三甲胺作增溶剂,记录560nm处Ni(Ⅱ)-Br-PADAP与Fe(Ⅱ)-Br-PADAP的峰值吸收之和746nm处Fe(Ⅱ)-Br-PADAP的吸不度测定了钠基合金中的镍和铁。两咱离子的定量线性范围分别为0.10-1.20mg/lL和0.20-1.60mg/L,检出限为0.02mg/L  相似文献   
949.
利用X-射线衍射,扫描电镜,拉曼光谱,等离子发射光谱和比表面测定等方法研究了不同状态下失活及新鲜催化剂的结构,杂种类及含量。结果表明,超温使催化剂晶化明显,制备方法对催化剂结构有直接影响,再生使其强度降低,条形催化剂比较容易粉化,无机杂质是次要的失活原因。  相似文献   
950.
在0.05 mol/L KCl底液中,β-环糊精(β-CD)-六次甲基四胺超分子络合物在2.5次微分极谱仪上于-0.78V(vs.SCE)处产生吸附还原波,峰形对称且稳定,其峰电流与六次甲基四胺浓度在4.0×10-4-1.0×10~mol/L之间呈良好线性关系;检出限为1.5×10-4mol/L。应用该法测定了有机工业产品六次甲基四胺,并与传统方法进行了比较,结果令人满意。对超分子络合物电化学性质及分子识别机理进行了探讨。  相似文献   
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