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21.
A highly regioselective Heck arylation, utilizing aryl triflates and a palladium/dppf catalytic system, can be performed at the internal, beta-carbon of Boc- and phthalimido-protected allylamines, yielding arylated primary allylamine equivalents. The very high regioselectivity obtained with secondary Boc-protected allylamides is suggested to be caused by an efficient coordination between an anionic nitrogen and palladium. Single-mode microwave irradiation has been utilized to shorten the reaction times and, in the case of Boc-protected allylamides, to improve the yields of two electron-poor aryl triflates. 相似文献
22.
H. v. Euler Margareta Rydbom H Hellström E. Remy E. A. Price und F. H. Carr 《Fresenius' Journal of Analytical Chemistry》1931,83(5-6):230-232
Ohne Zusammenfassung 相似文献
23.
Cristian Bodin Fredrik Mauritzson Rob Horsefield Anna Aagaard Hongwei Guo Linda Öster Lisa Wissler Margareta Ek 《Journal of synchrotron radiation》2012,19(2):288-289
Currently there is no rack system for the long‐term storage of SPINE pucks in spite of their commercial availability and heavy usage at the ESRF. The only way to store pucks is in transport dewar canisters which presents a number of limitations and drawbacks. Here a simple affordable rack for storing SPINE pucks is described, which we believe is accessible to not only synchrotrons but also both academic and industrial research laboratories. 相似文献
24.
25.
Ramström M Sandberg H 《European journal of mass spectrometry (Chichester, England)》2011,17(5):497-506
Vitamin K-dependent carboxylation of glutamic acid (Glu) residues into γ-carboxyglutamic acid (Gla) is a post-translational modification essential for normal protein activity of, for example, proteins involved in the blood coagulation system. These proteins may contain as many as 12 sites for γ-carboxylation within a protein sequence of 45 amino acid residues. In the biopharmaceutical industry, powerful analytical techniques are required for identification and localization of modified sites. We here present comparatively easy and rapid methods for studies of Gla-containing proteins using recent technology. The performances of two mass spectrometric fragmentation techniques, collision-induced dissociation (CID) and electron transfer dissociation (ETD), were evaluated with respect to γ-carboxylated peptides, applying on-line LC-ion trap MS. ETD MS has so far not been reported for Gla-containing peptides and the applicability of CID for heavily γ-carboxylated proteins has not been evaluated. The anticoagulant protein, protein C, containing nine Gla-sites, was chosen as a model protein. After tryptic digestion, three peptides containing Gla-residues were detected by MS; a 1.2 kDa fragment containing two Gla-residues, a 4.5 kDa peptide containing seven residues and also the 5.6 kDa tryptic peptides containing all nine Gla-residues. Regarding the shortest peptide, both CID and ETD provided extensive peptide sequencing. For the larger peptides, fragmentation by CID resulted in loss of the 44 Da CO(2)-group, while little additional fragmentation of the peptide chain was observed. In contrast, ETD resulted in comprehensive fragmentation of the peptide backbone. The study demonstrates that the combination of both techniques would be beneficial and complementary for investigation of γ-carboxylated proteins and peptides. 相似文献
26.
Carsten Bolm Konrad Weickhardt Margareta Zehnder Dorothea Glasmacher 《Helvetica chimica acta》1991,74(4):717-726
The synthesis of the complexes 3 of various metals ligated to chiral 4,5-dihydro-2-(2′-oxidophenyl-?O)oxazoles-?N is described (Scheme). Three of them, i.e. 3a , 3e , and 3f containing CuII, ZnII and NiII, respectively, were analyzed by X-ray diffraction studies. A series of CuII complexes ( 6a – d ) with differently substituted dihydrooxazoles have been synthesized. 相似文献
27.
Bernhard Spingler Jürgen F.K Müller Markus Neuburger Margareta Zehnder 《Journal of organometallic chemistry》1998,570(2):700
Bicyclic chiral phosphoric triamide 1 reacts after lithiation and addition with several electrophiles in a highly regio- and diastereoselective fashion. The stannylated product 2 can be recrystallised to a single diastereomer. Its X-ray analysis is the first solid state structure determination of a chiral hexamethylphosphoric triamide analogue. 相似文献
28.
Margareta Frenkel Fertig 《Acta Mathematica Hungarica》1966,17(3-4):457-459
Sans résumé
Présenté par
P. Turán 相似文献
29.
Hans Fritz Jean-Michel Henlin Thophile Tschamber Jacques Streith Andreas Riesen Margareta Zehnder 《Helvetica chimica acta》1988,71(4):822-834
Azeitidinodiazepines 4b and 4c react with acylnitroso dienophiles 5a–c , specifically from their convexe α-side, but in a non-regiospecific way, leading thereby stereospecifically to the expected adducts 6a–d and 7a–d . The three-dimensional structures of 6a and 7a were determined by X-ray analyses which corroborated their NMR data. OsO4 cis-glycolization occurred in good yield with the inverse adducts 7a and 7e and led to the rearranged products 10 . These latter ones result from an intramolecular N- to O-transbenzoylation of the short-lived intermediates 9 followed by fragmentation of the animal function. X-Ray analysis of 7a showed the N(10) atom to be pyramidal, a result which demonstrates that it does not have any pronounced benzamide character; otherwise no such N- to O-transbenzoylation would have taken place. Structure and relative configuration of 10a were ascertained by X-ray analysis which confirmed its NMR data as well as the stereochemical outcome of its formation. 相似文献
30.