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131.
Kahlich R Gleiter CH Laufer S Kammerer B 《Rapid communications in mass spectrometry : RCM》2006,20(2):275-283
A method for the liquid chromatography/tandem mass spectrometric (LC/MS/MS) quantification of piritramide, a synthetic opioid, in plasma after conventional off-line solid-phase extraction (SPE) and in urine by on-line SPE-LC/MS/MS in positive electrospray mode was developed and validated. Applicability of the on-line approach for plasma samples was also tested. Deuterated piritramide served as internal standard. For the off-line SPE plasma method mixed cation-exchange SPE cartridges and a 150 x 2 mm C18 column with isocratic elution were used. For the on-line SPE method, a Waters Oasis HLB extraction column and the same C18 analytical column in a column-switching set-up with gradient elution were utilized. All assays were linear within a range of 0.5-100 ng/mL with a limit of detection of 0.05 ng/mL. The intra- and interday coefficients of variance ranged from 1.3 to 6.1% for plasma and 0.5 to 6.4% for urine, respectively. The extraction recovery for the off-line plasma assay was between 90.7 and 100.0%. Influence of matrix effects, and freeze/thaw and long-term stability were validated for both approaches; influence of urine pH additionally for quantification in urine. 相似文献
132.
Dutheuil G Paturel C Lei X Couve-Bonnaire S Pannecoucke X 《The Journal of organic chemistry》2006,71(11):4316-4319
A highly stereospecific synthesis of (E)- or (Z)-alpha-fluoro-alpha,beta-unsaturated ketones 4, via a kinetically controlled Negishi palladium-catalyzed coupling reaction, was developed, providing an easy and general access to valuable fluorinated intermediates (pharmaceutical, peptide mimic, and so on). The synthesis involved a reaction between E/Z gem-bromofluoroolefins 2 and alkoxyvinylzinc species 6 under controlled reaction temperature. At 10 degrees C, (Z)-4 (70 to 99% yields) was obtained along with unreacted (Z)-2 (66 to 99% yields). At THF reflux, the recovered olefin was transformed into (E)-4 (up to 98% yield). 相似文献
133.
Mait Sylla-Iyarreta Veitía Pierre Louis Brun Pierre Jorda Annie Falguires Clotilde Ferroud 《Tetrahedron: Asymmetry》2009,20(18):2077-2089
Several commercially available nitrilases were investigated with regard to their potential to hydrolyze N-protected β3-amino nitriles into their corresponding N-protected β3-amino acids.The biotransformations were obtained in different proportions depending on the nitrilase involved. The best hydrolysis results were achieved for the N-Cbz-β3-amino nitrile from l-alanine using the NIT-107, in a phosphate buffer at 0.05 M. However, no biotransformation into the corresponding acids was observed for the N-sulfonylamide β3-amino nitriles. Two simple and efficient procedures to prepare the β3-amino nitriles from their analogous α-amino acids are described. Thirty four new substances were synthesized and characterized over the course of this work. 相似文献