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71.
Ramírez-Fernández J Botubol JM Bustillo AJ Aleu J Collado IG Hernández-Galán R 《Natural product communications》2011,6(4):443-450
The asymmetric synthesis of key fragments of the phytotoxic toxins botcinolide/botcinin is reported. The synthesis of 1 and 1a are based on a convergent route via esterification and alkene metathesis of fragments A, B or C, B, which were obtained by Evans aldol condensation and stereoselective crotylation, respectively. 相似文献
72.
Veloso A Astigarraga E Barreda-Gómez G Manuel I Ferrer I Giralt MT Ochoa B Fresnedo O Rodríguez-Puertas R Fernández JA 《Journal of the American Society for Mass Spectrometry》2011,22(2):329-338
Molecular mass images of tissues will be biased if differences in the physicochemical properties of the microenvironment affect
the intensity of the spectra. To address this issue, we have performed—by means of MALDI-TOF mass spectrometry—imaging on
slices and lipidomic analysis in extracts of frontal cortex, both from the same postmortem tissue samples of human brain.
An external calibration was used to achieve a mass accuracy of 10 ppm (1σ) in the spectra of the extracts, although the final assignment was based on a comparison with previously reported species.
The spectra recorded directly from tissue slices (imaging) show excellent s/n ratios, almost comparable to those obtained
from the extracts. In addition, they retain the information about the anatomical distribution of the molecular species present
in autopsied frozen tissue. Further comparison between the spectra from lipid extracts devoid of proteins and those recorded
directly from the tissue unambiguously show that the differences in lipid composition between gray and white matter observed
in the mass images are not an artifact due to microenvironmental influences of each anatomical area on the signal intensity,
but real variations in the lipid composition. 相似文献
73.
Daouda Ndiaye Maryame Sy Agnès Pallier Dr. Sandra Même Isidro de Silva Dr. Sara Lacerda Dr. Aline M. Nonat Dr. Loïc J. Charbonnière Dr. Éva Tóth 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(29):12056-12061
The search for more biocompatible alternatives to Gd3+-based MRI agents, and the interest in 52Mn for PET imaging call for ligands that form inert Mn2+ chelates. Given the labile nature of Mn2+, high inertness is challenging to achieve. The strongly preorganized structure of the 2,4-pyridyl-disubstituted bispidol ligand L1 endows its Mn2+ complex with exceptional kinetic inertness. Indeed, MnL1 did not show any dissociation for 140 days in the presence of 50 equiv. of Zn2+ (37 °C, pH 6), while recently reported potential MRI agents MnPyC3A and MnPC2A-EA have dissociation half-lives of 0.285 h and 54.4 h under similar conditions. In addition, the relaxivity of MnL1 (4.28 mm −1 s−1 at 25 °C, 20 MHz) is remarkable for a monohydrated, small Mn2+ chelate. In vivo MRI experiments in mice and determination of the tissue Mn content evidence rapid renal clearance of MnL1. Additionally, L1 could be radiolabeled with 52Mn and the complex revealed good stability in biological media. 相似文献
74.
José M. Isidro 《Central European Journal of Mathematics》2007,5(3):512-522
Let G be the Banach-Lie group of all holomorphic automorphisms of the open unit ball
in a J*-algebra
of operators. Let
be the family of all collectively compact subsets W contained in
. We show that the subgroup F ⊂ G of all those g ∈ G that preserve the family
is a closed Lie subgroup of G and characterize its Banach-Lie algebra. We make a detailed study of F when
is a Cartan factor.
相似文献
75.
76.
Cristina Pinedo-Rivilla Josefina Aleu Isidro G. Collado 《Tetrahedron: Asymmetry》2011,22(16-17):1653-1657
The transformation of (E)-2-benzylideneindan-1-one 1 by the filamentous fungi Botrytis cinerea, Trichoderma viride, and Eutypa lata as biocatalysts was studied. The results showed the catalytic potential of these fungi in affording several hydroxylation and reduction products, three of them reported here for the first time. The absolute configuration of enantiomerically pure 2-benzylindane derivatives was determined. 相似文献
77.
David Díez Ana B. Antón Javier Peña Pilar García Narciso M. Garrido Isidro S. Marcos F. Sanz Pilar Basabe Julio G. Urones 《Tetrahedron: Asymmetry》2010,21(7):786-793
This paper describes an anomalous behaviour of the Sharpless dihydroxylation of a terminal olefin. The synthesis of a new chiral pyrrolidine and its application as an organocatalyst in the Michael addition of cyclohexanone into nitrostyrenes are described. 相似文献
78.
79.
80.
The kinetics of the permanganate oxidation of formic acid in aqueous perchloric acid at 30°C were examined by the spectrophotometric method. The chemical reaction 2MnO + 3HCOOH + 2H+ → 2MnO2 + 3CO2 + 4H2O, appears to proceed via several parallel reactions. The overall rate equation has been obtained by using statistical multilinear regression analysis of the 660 cases studied, and the presence in the rate equation of two new terms in relation to previous studies shows that both permanganate autocatalytic effects and acid media inhibition must be taken into account when the reaction proceeds at constant ionic strength. 相似文献