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71.
K. J. Hotappel Schimmel & Co. R. E. Meyer und Dauphin Schimmel 《Fresenius' Journal of Analytical Chemistry》1930,80(5-6):236-237
Ohne Zusammenfassung 相似文献
72.
Saskia Thurnhofer 《Tetrahedron》2007,63(5):1140-1145
We developed an enantioselective synthesis for the food-relevant anteiso-fatty acids a15:0, a16:0, and a17:0. Different (carboxyalkyl)triphenylphosphonium bromide salts were coupled with (S)-3-methylpentanal in a Wittig reaction. Mixtures of the obtained cis-/trans-isomers were separated by Ag+-HPLC to give the novel cis-isomers of (S)-(+)-a15:1n-5, (S)-(+)-a16:1n-5, and (S)-(+)-a17:1n-5. Hydrogenation of the monoenoic products led to (S)-(+)-a15:0, (S)-(+)-a16:0, and (S)-(+)-a17:0, which are essential for the assessment of the bioactivity of tests with standards of anteiso-fatty acids. 相似文献
73.
Schimmel u. Co. 《Analytical and bioanalytical chemistry》1906,45(9-10):662-662
74.
Saskia Schulthoff James Y. Hamilton Marc Heinrich Yonghoon Kwon Conny Wirtz Alois Fürstner 《Angewandte Chemie (International ed. in English)》2021,60(1):446-454
Total synthesis allowed the constitution of the cytotoxic marine macrolides of the formosalide family to be confirmed and their previously unknown stereostructure to be assigned with confidence. The underlying blueprint was inherently modular to ensure that each conceivable isomer could be reached. This flexibility derived from the use of strictly catalyst controlled transformations to set the stereocenters, except for the anomeric position, which is under thermodynamic control; as an extra safety measure, all stereogenic centers were set prior to ring closure to preclude any interference of the conformation adopted by the macrolactone rings of the different diastereomers. Late‐stage macrocyclization by ring‐closing alkyne metathesis was followed by a platinum‐catalyzed transannular 6‐exo‐dig hydroalkoxylation/ketalization to craft the polycyclic frame. The side chain featuring a very labile unsaturation pattern was finally attached to the core by Stille coupling. 相似文献
75.
The new intermetallic type-I clathrate Na8Zn4Ge42 was obtained by direct reaction of the elements, and its crystal structure was determined by means of single-crystal X-ray diffraction methods. The structure is described in space group Pm3 n (no. 223) with a = 10.6982(1) Å. A mixed Zn/Ge occupancy is found for one of the network sites (6c). Na8Zn4Ge42 represents an air-stable electron-precise Zintl phase with exclusively Na cations located in the cavities of a polyanionic host network of four-connected Zn and Ge atoms. 相似文献
76.
77.
78.
Vladislava Timofeeva José Miguel Léon Baeza Dr. Raphael Nougué Dr. Mikhail Syroeshkin Prof. Dr. Rene Segundo Rojas Guerrero Dr. Nathalie Saffon-Merceron Dr. Gül Altınbaş Özpınar Dr. Saskia Rathjen Prof. Dr. Thomas Müller Dr. Antoine Baceiredo Dr. Tsuyoshi Kato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(44):e202201615
A stable (amino)plumbylene-substituted phosphaketene 3 was synthesized by the successive reactions of PbCl2 with two anionic reagents (lithium amidophosphine and NaPCO). Of particular interest, the thermal evolution of 3 , at 80 °C, leads to the transient formation of corresponding amino- and phosphanylidene-phosphaketenes ( 6 and 7 ), via a reductive elimination at the PbII center forming new N−P and P−P bonds. Further evolution of 6 gives a new cyclic (amino)phosphanylidene phosphorane 4 , which shows a unique reactivity as a phosphinidene. This result provides a new synthetic route to phosphinidenes, extending and facilitating further their access. 相似文献
79.
Jian‐Qiang Wang Dr. Saskia Stegmaier Bernhard Wahl Dr. Thomas F. Fässler Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(6):1793-1798
The endohedral stannaspherene cluster anion [Ir@Sn12]3? was synthesized in two steps. The reaction of K4Sn9 with [IrCl(cod)]2 (cod: 1,5‐cyclooctadienyl) in ethylenediamine (en) solution first yielded the [K(2,2,2‐crypt)]+ salt (2,2,2‐crypt: 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) of the capped cluster anion [Sn9Ir(cod)]3?. Subsequently, crystals of this compound were dissolved in en, followed by the addition of triphenylphosphine or 1,2‐bis(diphenylphosphino)ethane and treatment at elevated temperatures. [Ir@Sn12]3? was obtained and characterized as the [K(2,2,2‐crypt)]+ salt. The isolation of [Sn9Ir(cod)]3? as an intermediate product establishes that the formation of the stannaspherene [Ir@Sn12]3? occurs through the oxidation of [Sn9Ir(cod)]3?. Among the structurally characterized tetrel cluster anions, [Ir@Sn12]3? is a unique example of a stannaspherene, and one of the rare spherical clusters encapsulating a metal atom that is not a member of Group 10. Single‐crystal structure determination shows that the novel Zintl ion cluster has nearly perfect icosahedral Ih point symmetry. 相似文献
80.
Assessment of commutability for candidate certified reference material ERM-BB130 “chloramphenicol in pork” 总被引:1,自引:0,他引:1
Reinhard Zeleny Håkan Emteborg Heinz Schimmel 《Analytical and bioanalytical chemistry》2010,398(3):1457-1465
Chloramphenicol (CAP), an effective antibiotic against many microorganisms, is meanwhile banned in the EU for treatment of
food-producing animals due to adverse health effects. The Institute for Reference Materials and Measurements (IRMM) is currently
developing a certified reference material (CRM) for CAP in pork, intended for validation and method performance verifications
of analytical methods. The material will be certified using liquid chromatography–tandem mass spectrometry (LC–MS/MS) and
gas chromatography–mass spectrometry (GC–MS) methods and has a target CAP level around the minimum required performance limit
(MRPL) of 0.3 μg/kg. To prove that the material can be applied as a quality control tool for screening methods, a commutability
study was conducted, involving five commercially available enzyme-linked immunosorbent assay kits and one biosensor assay
(BiaCore kit). Meat homogenates (cryo-milled wet tissue) with CAP concentrations around the MRPL and the candidate CRM (lyophilised
powder) were measured by LC–MS/MS and GC–MS as well as the six screening methods. Pairwise method comparisons of results obtained
for the two sample types showed that the CRM can successfully be applied as quality control (QC) sample to all six screening
methods. The study suggests that ERM-BB130 is sufficiently commutable with the investigated assays and that laboratories applying
one of the investigated kits therefore benefit from using ERM-BB130 to demonstrate the correctness of their results. However,
differences among the assays were observed, either in the abundance of bias between screening and confirmatory LC and GC methods,
the repeatability of test results, or goodness of fit between the methods. 相似文献