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31.
Armin Dietrich Birgit Maas Wilhelm Messer Günther Bruche Volker Karl Astrid Kaunzinger Armin Mosandl 《Journal of separation science》1992,15(9):590-593
The characteristics of the new chiral stationary phase heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin are outlined and compared with permethyl- and perethyl-β-cyclodextrins. 相似文献
32.
The electron density difference in a NaSCN crystal is set up from the ab initio densities of Na+ and SCN? ions and compared to the experimental counterpart based on X-ray diffraction measurements. Numerical integration over the electron density difference is executed around the Na+ ion. The atomic charge (+0.20e) derived in this way is in good agreement with the analogous experimental charge (+0.27e) The low experimental value cannot therefore be taken as an indication for a predominantly non-ionic structure of NaSCN and similar sodium salts 相似文献
33.
Amidine als Zwischenprodukte bei Umamidierungsreaktionen. 9. Mitteilung über Umamidierungsreaktionen
Christian Heidelberger Armin Guggisberg Euripides Stephanon Manfred Hesse 《Helvetica chimica acta》1981,64(2):399-406
Amidines as Intermediates in Transamidation Reactions By loss of water in the presence of p-toluenesulfonic acid/xylole N-aminoalkyllactames form bicyclic amidines. The corresponding N-alkylaminoalkyl-lactames' react to bicyclic amidinium salts or to transamidated products, ring-enlarged by the N-alkylamino residue, respectively (s. Scheme 1). The bicyclic amidines and amidinium salts are partially hydrolyzed by KOH/H2O to lactames (s. Scheme 2). Which of the two possible isomeric lactames are formed is discussed. 相似文献
34.
This paper presents a short synthesis of oncinotin-11-one ( 11 ), a minor alkaloid of Oncinotis tenuiloba (Apocynaceae). Based on a disconnection approach, the spermidine portion of the key intermediate 6 was constructed consecutively by simple N-alkylations starting from ethyl piperidine-2-carboxylate ( 1 ). Treatment of 6 with in situ lithiated 2-[(10-bromodecyl)oxy]tetrahydropyran resulted in the formation of the keto moiety under simultanous deprotection of the lactam N-atom to give the amino ketone 7 in 71% yield. Cleavage of the tetrahydro-2H-pyran-2-yl(Thp) portion and Jones oxidation of the resulting alcohol 8 gave the amino acid 9 which was cyclized. Final N-debenzylation of 10 provided the natural alkaloid 11 . Only two protective groups were needed in this synthesis. The reaction of N-alkyl-lactams with organometallic reagents is discussed. 相似文献
35.
Armin Herzer 《Journal of Geometry》1979,12(2):104-131
Every affine central collineation of a translation plane induces a special collineation of the projective space spanned by the spreadF belonging to . Here the relations between these special collineations of and certain incidence propositions inF are investigated; so new proofs are given for some characterisations of (A,B)-regular spreads included in [7]. 相似文献
36.
Konstantin N. Gavrilov Alexei A. Shiryaev Ilya V. Chuchelkin Sergey V. Zheglov Eugenie A. Rastorguev Vadim A. Davankov Armin Börner 《Tetrahedron: Asymmetry》2012,23(14):1052-1057
New P,P-bidentate diastereomeric diphosphoramidite chiral ligands with mixed stereogenic elements and a C1 backbone symmetry have been prepared from (Sa)- and (Ra)-1,1′-binaphthyl-2,2′-diol (BINOL) and (S)-N-benzyl-1-(pyrrolidin-2-yl)methanamine and are fully characterized. The use of these ligands provides up to 84% ee in the Pd-catalyzed asymmetric allylic substitution of (E)-1,3-diphenylallyl acetate and up to 95% ee in the Rh-catalyzed asymmetric hydrogenation of α-dehydrocarboxylic acid esters. The results indicate that the catalytic performance is highly affected by the axial chirality of the binaphthyl moieties of the ligand and the nature of the solvent. 相似文献
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Bjoern Moosmann Laura M. Huppertz Melanie Hutter Armin Buchwald Sascha Ferlaino Volker Auwärter 《Journal of mass spectrometry : JMS》2013,48(11):1150-1159
The appearance of pyrazolam in Internet shops selling ‘research chemicals’ in 2012 marked the beginning of designer benzodiazepines being sold as recreational drugs or ‘self medication’. With recent changes in national narcotics laws in many countries, where two uncontrolled benzodiazepines (phenazepam and etizolam), which were marketed by pharmaceutical companies in some countries, were scheduled, clandestine laboratories seem to turn to poorly characterized research drug candidates as legal substitutes. Following the appearance of pyrazolam, it comes with no surprise that recently, flubromazepam (7‐bromo‐5‐(2‐fluorophenyl)‐1,3‐dihydro‐2H‐1,4‐benzodiazepin‐2‐one), a second designer benzodiazepine, was offered on the market. In this article, this new compound was characterized using nuclear magnetic resonance, gas chromatography‐mass spectrometry (GC–MS), liquid chromatography–mass spectrometry (LC–MS/MS) and liquid chromatography quadrupole time‐of‐flight MS (LC–Q–ToF–MS). Additionally, a study was carried out, in which one of the authors consumed 4 mg of flubromazepam to gain preliminary data on the pharmacokinetic properties and the metabolism of this compound. For this purpose, serum as well as urine samples were collected for up to 31 days post‐ingestion and analyzed applying LC–MS/MS and LC–Q‐ToF‐MS techniques. On the basis of this study, flubromazepam appears to have an extremely long elimination half‐life of more than 100 h. One monohydroxylated compound and the debrominated compound could be identified as the predominant metabolites, the first allowing a detection of a consumption for up to 28 days post‐ingestion when analyzing urine samples in our case. Additionally, various immunochemical assays were evaluated, showing that the cross‐reactivity of the used assay seems not to be sufficient for safe detection of the applied dose in urine samples, bearing the risk that it could be misused in drug‐withdrawal settings or in other circumstances requiring regular drug testing. Furthermore, it may be used in drug‐facilitated crimes without being detected. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献