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141.
Yabuuchi N Yamakawa Y Yoshii K Komaba S 《Dalton transactions (Cambridge, England : 2003)》2011,40(9):1846-1848
A nearly single-phase of a low-temperature (LT) phase of Li(2)FeSiO(4) is prepared by a hydrothermal method at 150 °C. We report the detailed crystal structure of LT-Li(2)FeSiO(4) (S.G. Pmn2(1)) by applying Rietveld/MEM analysis to the synchrotron XRD pattern. LT-Li(2)FeSiO(4) shows 150 mA h g(-1) as the positive electrode materials of rechargeable batteries. 相似文献
142.
Construction of carbocyclic ring of indoles using ruthenium-catalyzed ring-closing olefin metathesis
The selective synthesis of substituted indoles was achieved by the ring-closing olefin metathesis (RCM)/elimination sequence or the RCM/tautomerization sequence of functionalized pyrrole precursors. The RCM/elimination sequence was also applied to double ring closure to yield a substituted carbazole. 相似文献
143.
Zeng J Wang W Deng P Feng W Zhou J Yang Y Yuan L Yamato K Gong B 《Organic letters》2011,13(15):3798-3801
Hydrogen-bonded zippers bearing terminal alkene groups were treated with Grubbs' catalyst, leading to covalently cross-linked zippers without violating H-bonding sequence specificity. The yield of a cross-linked zipper depended on the stability of its H-bonded precursor, with a weakly associating pair giving reasonable yields only at high concentrations while strongly associating pairs showed nearly quantitative yields. The integration of thermodynamic (H-bonding) and kinetic (irreversible C═C bond formation) processes suggests the possibility of developing many different covalent association units for constructing molecular structures based on a self-assembling way. 相似文献
144.
Takashima-Hirano M Tazawa S Takahashi K Doi H Suzuki M 《Chemical & pharmaceutical bulletin》2011,59(8):1062-1064
Ramelteon (TAK-375) is a novel melatonin receptor agonist that is used for clinical treatment of insomnia. The present report describes radiolabeling of ramelteon with the short-lived positron-emitter 11C (T(1/2)=20.4 min) by 2 methods. One method was [11C]methylation of an acetoamide precursor and the other was [11C]acylation of the corresponding amine precursor. First, [11C]methylation method showed the low reproducibility together with the production of many kinds of side products from which the [11C-methyl]Ramelteon was separated with chemical purity of <28% and radiochemical purity of >98%. Whereas, the [11C]acylation method showed high efficiency and reproducibility with a good radiochemical yield (22-43%, decay corrected), high chemical and radiochemical purities (>99% each), and high specific activity (43-162 GBq/μmol) (n=5) after HPLC purification. [11C]Ramelteon is a potential positron emission tomography (PET) probe for imaging the melatonin receptor. 相似文献
145.
Akiko Watanabe Naotoshi Kiyota Tetsuo Yamasaki Kazuhiro Tanda Tatsunori Miyagoe Masanori Sakamoto Masami Otsuka 《Journal of heterocyclic chemistry》2011,48(5):1132-1139
Four isomers of the monomer of peptide nucleic acid (PNA) were derived from (2S,4R)‐4‐hydroxyproline; they had different stereochemistries at the C2 and C4 positions in the pyrrolidine ring. These different backbone conformations corresponding to four different stereochemistries were realized through a combination of inversions at the C2 and the C4 positions in pyrrolidine ring. The obtained backbone frameworks were reacted with N‐benzoyl thymine to give the corresponding PNA monomers. Spectroscopic comparison of the resultant monomers confirmed their stereochemistries. J. Heterocyclic Chem., (2011). 相似文献
146.
We have shown from in situ synchrotron x-ray diffraction measurements that there are two thermodynamically stable liquid forms of SnI(4), depending on the pressure. Based on the liquid-liquid critical point scenario, our recent measurements suggest that the second critical point, if it exists, may be located in a region close to the point at which the melting curve of the crystalline phase abruptly breaks. This region is, unlike that of water, experimentally accessible with relative ease. 相似文献
147.
The new carboxamide protecting group, 4-(tert-butyldimethylsiloxy)-2-methoxybenzyl (SiMB), has been developed. While this SiMB group can be removed using mild basic desilylation methods, it can also be deprotected under strongly acidic or oxidative conditions. An application of this group to simple carboxamide groups, as well as to more complex and acid-sensitive adenosine derivatives containing a cyclophane scaffold, was also demonstrated. 相似文献
148.
Miyazaki M Ando N Sugai K Seito Y Fukuoka H Kanemitsu T Nagata K Odanaka Y Nakamura KT Itoh T 《The Journal of organic chemistry》2011,76(2):534-542
A catalytic asymmetric allylation of 3,4-dihydroisoquinoline was carried out with allyltrimethoxylsilane-Cu as the nucleophile in the presence of DTBM-SEGPHOS as the chiral ligand to afford corresponding chiral 1-allyltetrahydroisoquinoline derivatives in good yield and stereoselectivity. The allyl adduct thus obtained was applied to the synthesis of several isoquinoline alkaloids such as crispine A and homolaudanosine. The reaction was further used for the synthesis of the isoquinoline moiety of schulzeine A. 相似文献
149.
A combination of dimethyl sulfoxide (DMSO) and trifluoroacetic anhydride (TFAA) mediates functionalization at the 2α-position of indole derivatives. Carbon and heteroatom nucleophiles were directly introduced via a one-pot procedure in excellent yields. 相似文献
150.
Depending on protein environment, a single photofunctional chromophore shows a wide variation of photoabsorption/emission energies. This photobiological phenomenon, known as color tuning, is observed in human visual cone pigments, firefly luciferase, and red fluorescent protein. We investigate the origin of color tuning by quantum chemical calculations on the excited states: symmetry-adapted cluster-configuration interaction (SAC-CI) method for excited states and a combined quantum mechanical (QM)/molecular mechanical (MM) method for protein environments. This Minireview summarizes our theoretical studies on the above three systems and explains a common feature of their color-tuning mechanisms. It also discuss the possibility of artificial color tuning toward a rational design of photoabsorption/emission properties. 相似文献