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1.
《Inorganica chimica acta》1986,122(2):243-248
The reaction of [IrCl(COD)]2 with K[CH(N-p- C6H4CH3)2] (K+form−) has been carried out in both neat toluene and in the presence of ButOH. In the first case [Ir(form)(COD)]2 (1) was obtained in good yields. The other reaction follows a somewhat different course with partial alcoholysis of the formamidine ligand and formation of Ir2(μ-form)(μ-NH-p-C6H4CH3)(COD)2 (2). Crystal data for compound 2: space group P21/c, a = 9.389(2), b = 21.083(4), c = 16.810(2) Å, β = 91.54(1)° V=3326(2) Å3, Z = 4, R = 0.0343 for 3707 data with Fo2 > 3σ(Fo2). 相似文献
2.
Katsuya Koike Mamoru Sugimoto Yoshiaki Nakahara Tomoya Ogawa 《Glycoconjugate journal》1985,2(2):105-108
The cerebrosides were first isolated by Thudicum in 1874 and the structures were established by Carteret al. in 1950 (for review, see [2]). In 1961 Shapiro and Flowers [3] reported the first total synthesis of a cerebroside1 (Fig. 1) which was identified with the natural sample, only through comparison of their i.r. data. In order to confirm the absolute configuration at C-2 of natural cerebroside1, we describe here an unambiguous synthesis of two stereoisomeric cerebrosides1 and2, and found that the1H-NMR spectra of the synthetic1 (Fig. 2) was completely identical with that of the natural cerebroside reported recently by Dabrowskiet al. [4].In planning the synthetic route, the target structures1 and2 were disconnected at the dotted lines to give three key synthetic intermediates3, 4 and5 or6 (Fig. 1).Abbreviations Bu
butyl
- Ph
phenyl
-
t-BuPh2SiCl
t-butyldiphenylsilyl chloride
- MTPA
-methoxy--trifluoromethylphenylacetic acid
- THF
tetrahydrofuran
Part 36 in the series Synthetic Studies on Cell-surface Glycans, for part 35, see [1] 相似文献
3.
《Carbohydrate research》1987,162(2):237-246
Total syntheses of both (2S, 3R, 4E)-1-O-β-d-galactopyranosyl-N-(2′R)-2′-hydroxytetracosanoylsphingenine 23 and the (2′S) stereoisomer were performed in an unambiguous way by employing either (2S, 3R, 4E)-N-(2′R)-2′-(tert-butyl-diphenylsilyloxy)tetracosanoylsphingenine or its (2′S) stereoisomer as the key glycosyl acceptors. The synthetic cerebroside 23 was shown to be identical with the natural product through comparison of their 400-MHz, 1H-n.m.r. spectra, thus providing synthetic evidence for the 2′R configuration of the natural cerebroside. 相似文献
4.
Liang Junxi Wang Yanbin Zhang Qiang Li Yu Geng Zhiyuan Wang Xiuhong 《Journal of molecular modeling》2013,19(4):1739-1750
Gas-phase reactions of ClO–/BrO– with RCl (R = CH3, C2H5, and C3H7) have been investigated in detail using the popular DFT functional BHandHLYP/aug-cc-pVDZ level of theory. As a result, our findings strongly suggest that the type of reaction is firstly initiated by a typical SN2 fashion. Subsequently, two competitive substitution steps, named as SN2-induced substitution and SN2-induced elimination, respectively, would proceed before the initial SN2 product ion-dipole complex separates, in which the former exhibits less reactivity than the latter. Those are consistent with relevant experimental results. Moreover, we have also explored reactivity difference for the title reactions in term of some factors derived from methyl group, p-π electronic conjugation, ionization energy (IE), as well as molecular orbital (MO) analysis. Figure
Energy profiles for the ClO– reactions and BrO–reactions, respectively 相似文献
5.
Elke Duchardt Christian Richter Bernd Reif Steffen J. Glaser Joachim W. Engels Christian Griesinger Harald Schwalbe 《Journal of biomolecular NMR》2001,21(2):117-126
A new heteronuclear NMR pulse sequence for the measurement of nJ(C,H) coupling constants, the /selective HC(C)H-TOCSY, is described. It is shown that the S3E element (Meissner et al., 1997a,b) can be used to obtain spin state selective coherence transfer in molecules, in which adjacent CH moieties are labeled with 13C. Application of the / selective HC(C)H-TOCSY to a 10nt RNA tetraloop 5-CGCUUUUGCG-3, in which the four uridine residues are 13C labeled in the sugar moiety, allowed measurement of two bond and three bond J(C,H) coupling constants, which provide additional restraints to characterize the sugar ring conformation of RNA in cases of conformational averaging. 相似文献
6.
《Bioscience, biotechnology, and biochemistry》2013,77(9):1726-1730
As a model experiment for the stereoselective synthesis of optically active cis-α,β-dibenzyl-α-hydroxy-γ-butyrolactone, (2R, 3S)-2-benzyl-2-hydroxy-3-(3,4-methylenedioxybenzyl)-γ-butyrolactone (3) was stereoselectively synthesized from L-(+)-arabinose. 相似文献
7.
《Inorganica chimica acta》1986,115(1):L19-L21
8.
《Inorganica chimica acta》2006,359(9):2859-2863
Terminal alkynes (R–CC–H, R = 1-naphthyl, 9-anthryl, 4-Me2N–C6H4–, or the longer analogue, 4-(4-Me2N–C6H4–CC–)–C6H4–) react with [Rh(PMe3)4Me] at ambient temperature, with loss of methane and one PMe3 ligand, to form the corresponding mer,trans-[(PMe3)3Rh(CCR)2H] compounds in excellent yield. In this preliminary study, the synthesis and spectroscopic characterization of the four new compounds are reported, along with the single-crystal structure of the R = 4-Me2N–C6H4 derivative. 相似文献
9.
10.
Fátima M.F. Vergara Maria das G.M.O. Henriques André L.P. Candea Jim L. Wardell Marcus V.N. De Souza 《Bioorganic & medicinal chemistry letters》2009,19(17):4937-4938
A series of 11 α,ω-diaminoalkanes, (H2N(CH2)nNH2, n = 2–12) have been evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Compounds, (H2N(CH2)nNH2, n = 9–12), exhibited a very good activities in the range 2.50–3.12 μg/mL, which can be compared with that of the first line drug, ethambutol (3.12 μg/mL). These results and a preliminary QSAR study can be considered an important start point for the rational design of new leads for anti-TB compounds. 相似文献
11.
12.
《Inorganica chimica acta》2006,359(9):2896-2909
[RuCl3(NO)(P–P)], [P–P = R2P(CH2)nPR2 (n = 1–3) and R2P(CH2)POR2, PR2–CHCH–PR2, R = Ph and (C6H11)2P-(CH2)2-P(C6H11)2] were obtained and characterized by 31P {1H} NMR, IR spectroscopies and cyclic voltammetry. The structures of fac-[RuCl3(NO)(P–P)], P–P = dppm (1), dppe (2), c-dppen (3) and dppp (4), mer-[RuCl3(NO)(dcpe)] (6a) and mer-[RuCl3(NO)(dppmO)] (7) have been determined by X-ray diffraction. Photochemical isomerization of fac- to mer-[RuCl3(NO)(P–P)] was observed under white light in a CH2Cl2 solution and in solid state. The isomerization processes were followed by IR and 31P {1H} spectra. The mer-[RuCl3(15NO)(dppb)] isomer was used for the definition of the phosphorus atoms in the structure of the complex in solution. The electrochemical study shows that the oxidation/reduction processes observed in these complexes are dependent on both the isomer (fac or mer) and the solvent. In CH2Cl2, the NO+ reduction potentials are less negative for the mer-isomers than for the fac ones, while in CH3CN solvent these potentials are, in general, very close for both isomers. 相似文献
13.
14.
J. Wilson Quail Louis T.J. Delbaere Alan R.P. Paterson 《Nucleosides, nucleotides & nucleic acids》2013,32(5):877-885
Abstract The molecular structure of N6-(4-nitrobenzyl)-β-D-2′-deoxyadenosine (I) has been determined by single crystal X-ray diffraction. A potent inhibitor of adenosine permeation in cultured S49 mouse lymphoma cells, I binds tightly (KD 2.4 nM) to high affinity membrane sites present on the nucleoside transporter elements of these cells. Compound I crystallizes in the trigonal space group P3221 with unit cell dimensions a = b = 8.0009(9)Å, c = 49.174(8)Å, and Z = 6. The structure was solved by direct methods and refined by least-squares to a final R = 0.038. The mean plane of the 4-nitrobenzyl group, an important substituent for potent nucleoside transport inhibition in a series of S6-substituted 6-thioinosine derivatives, is inclined at an angle of 120.6° to the plane of the adenine ring. The torsion angles around the methylene carbon atom of this benzyl group are C(6)-N(6)-C(10)-C(11), 96.6° and N(6)-C(10)-C(11)-C(12), 93.6°. The glycosidic torsion angle, X, is 217.1° which corresponds to the common anti nucleoside conformation. The deoxyribose ring, however, has the unusual C(1′)-exo conformation, with C(1′) displaced 0.608Å from the plane of C(2′), C(3′), C(4′) and O(4′). The conformation about the exocyclic C(4′)-C(5′) bond is gauche+. 相似文献
15.
《Inorganica chimica acta》1986,122(1):111-118
The title complex, prepared in 1 M NaOH, was crystallized from hot N,N-dimethylformamide/ ethanol solutions to give Na12[Ce(C6H2O2(SO3)2)4]· 9H2O·6DMF. The purple—brown crystals were examined by X-ray diffraction while inside quartz capillaries filled with DMF, (λmax 425 nm, ϵ 3664; λsh 520 nm, ϵ 2240) and belong to space group Pbca, Z=8 with a=21.846(4), b=17.348(2), c=43.103- (6) Å, V=16.335(7) Å3, Dc=1.693 gcmt−3, Do=1.725 g cmt−3. Diffractometer data were collected using Mo Kα radiation to 2θ=43o. For 7331 independent data with Fo2>3σ(Fo2) full matrix least squares refinement converged to unweighted and weighted R factors of 0.072 and 0.110, respectively, with a mixture of anisotropic and isotropic thermal parameters. The disordered DMF atom parameters were not refined. The structure consists of discrete monomeric Ce(C6H2S2O8)412− units with 12 Na+ counter cations and 10 H2O molecules (two with half occupancy), and 6 DMF molecules of solvation filling up spaces between cations and anions. Cerium(IV) is in a general position with a coordination polyhedron close to the trigonal-faced dodecahedron, D2d, with the angles between the two BAAB trapezoids of 2.3o and 3.7o. The average CeO(A) distance, 2.363(9) Å is longer than the average CeO(B) distance, 2.326(15)Å, with the reverse being true for one of the four tironato ligands. The average ring OCeO angle is 67.9(1)o. The cerium (IV) complex is found by cyclic voltammetry to undergo a quasi-reversible one-electron reduction (in strongly basic solution with excess tiron) with Ef=−497 mV vs. SCE, hence the ratio of the formation constants for tetrakis(tironato)cerate(IV) to that for tetrakis(tironato)cerate(III), KIV/KIII, is 1033. Characterization of other tiron salts is reported. 相似文献
16.
Shigeki Hamaguchi Junzo Hasegawa Hajime Kawaharada Kiyoshi Watanabe 《Bioscience, biotechnology, and biochemistry》2013,77(8):2055-2059
Enzymes and microorganisms were screened for the asymmetric hydrolysis of (R, S)-5-acetoxymethyl-3-tert-butyl-oxazolidin-2-one 1. Lipases from Pseudomonas aeruginosa and Alcaligenes species, and microorganisms which belong to Enterobacter species or Klebsiella species were found to hydrolyze 1 enantioselectively to give (R)-5-hydroxymethyl-3-tert-butyl-oxazolidin-2-one (R)-2 and (S)-l. (S)-2, one of the typical intermediates for preparing optically active β-blocking agents (β-blockers), was obtained with high enantiomeric excess (91~98% e.e.) from (S)-1. 相似文献
17.
《Bioscience, biotechnology, and biochemistry》2013,77(10):1709-1711
For use as the internal standards in a quantitative analysis of natural jasmonic acid (JA) and methyl jasmonate (JAMe) by gas chromatography-mass spectrometry-selected ion monitoring, (±)-2-(2,3–2H2)JA and its methyl ester, (±)-2-(2,3–2H2)JAMe, were efficiently prepared from 2-(2–pentyl)-2-cyclopentenone through catalytic semi-deuteriogenation of acetylenic intermediates with deuterium gas in pyridine. 相似文献
18.
《Inorganica chimica acta》1988,142(1):165-168
Some luminescent properties of single crystals of Eu(NO3)3·6H2O are reported at temperatures down to liquid helium. The water molecules are responsible for a considerable amount of quenching of the emission. The Eu3+ coordination changes upon lowering the temperature. The number of 5D0-7F2 lines observed is higher than expected. 相似文献
19.
Hiroshi Ohrui Tsutami Misawa Hiroshi Meguro 《Bioscience, biotechnology, and biochemistry》2013,77(7):1825-1829
The photobromination of 1,5-anhydro-2,3-O-isopropylidene-β-d-ribofuranose gave the corresponding (5S)-5-bromo compound. The reduction of the bromide with triphenyltindeuteride gave (5S)-(5-2H1)-1,5-anhydro-2,3-O-isopropylidene-β-d-ribofuranose, with a chiral purity of 76% at C-5, which was converted to (5R)- and (5S)-(5-2H1)-d-riboses and other ribofuranose derivatives. 相似文献
20.
Fumio Sugawara Haruhiko Nakayama Gary A. Strobel Tomoya Ogawa 《Bioscience, biotechnology, and biochemistry》2013,77(9):2261-2271
The stereoselective synthesis of 1- and 2-O-α-d-cellotriosyl-3-deoxy-2(R)- and 2(S)-glycerols, which determined the structure of rhynchosporoside produced by Rhynchosporium secalis, and their phytotoxicity toward the host plant (Hordeum vulgare) are described in detail. 相似文献