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991.
992.
Wolfgang Hanefeld Martin Schlitzer Norbert Debski Helmut Euler 《Journal of heterocyclic chemistry》1996,33(4):1143-1146
3-Aminorhodanine 2 was reacted with cyclic anhydrides yielding 3-(2,5-dioxopyrrolidin-1-yl), 3-(2,6-dioxopiperidin-1-yl), and 3-(1,3-dioxoisoindolin-2-yl)rhodanine 6-8 , which in turn were condensated in 5 position with several aldehydes yielding the new rhodanine derivatives 9-11 . 相似文献
993.
Ursula Schmid Heinz Heimgartner Hans Schmid Peter Schnholzer Helmut Link Karl Bernauer 《Helvetica chimica acta》1975,58(7):2222-2227
Structure of a Stable Dipolar Compound from 2,2-Dimethyl-3-dimethylamino-2H-azirine and Benzoylisothiocyanate. Benzoylisothiocyanate and 2,2-dimethyl-3-dimethylamino-2H-azirine ( 1 ) react to given the dipolar compound 4,4-dimethyl-2-thiazolin-5-dimethylimminium-2-benzcarboxamidate ( 2 ), whose structure has been proved by X-ray analysis. Compound 2 , upon addition of water, yields the thiourea derivative 3 , whereas by acid catalyzed hydrolysis the thiazolinone derivative 4 is formed. The dipolar structure 2 is also existent in organic solvents like dimethylsulfoxide or chloroform. 相似文献
994.
995.
Helmut Fischer David Reindl Carsten Troll 《Journal of organometallic chemistry》1994,480(1-2):221-225
The successive reaction of chromium and tungsten hexacarbonyl, (CO)6M (M = Cr, W), with [N=C(Ph)R]− and [Et3O]BF4 yields the alkylideneamino(ethoxy)carbene complexes (CO)5M[C(OEt)N=C(Ph)R] (M = Cr (1), W (2); R = NMe2 (a), tBu (b)). Ethoxide abstraction from 1 and 2 affords 2-azoniaallenylidene complexes, {(CO)5M[CNC(Ph)R]}+BF4− (3/4). The complexes 3 and 4 are best described as resonance hybrids of several limiting structures. On the basis of the spectroscopic data of the complexes 3a and 4a the limiting structure of an iminium-substituted isocyanide complex dominates. 相似文献
996.
(R)-Malic, (S)-malic, (R)citramalic, (S)-citramalic, (2R,3S)-2-hydroxy-3-methyl-succinic and (2R,3S)-2,3-dimethyl-2-hydroxysuccinic acid were prepared on scales up to 25 mmol by stereospecific addition of water to different 2-butene-1,4-dioic acid derivatives catalyzed by resting cells of Clostridium formicoaceticum (Scheme 1). The (3R)-monodeuterio (R)- and (S)-malic acid as well as (R)- and (S)-citramalic acid were prepared using freeze-dried cells in 2H2O-buffer. The stereochemical purity of the products was in most cases ≥ 99%. 相似文献
997.
Wagner Y Sickmann A Meyer HE Daum G 《Journal of the American Society for Mass Spectrometry》2003,14(9):1003-1011
The analysis of macromolecular protein complexes is an important factor in understanding most cellular processes, e.g., protein transport into cell organells, signal transduction via biological membranes, apoptosis, energy metabolism, directed motion of cells, and cell division. These complexes are not only built of various numbers of different proteins but also of prosthetic groups and RNA molecules. To understand the role each protein plays in a complex, a complete analysis of all protein compounds is necessary. Therefore, several separation steps have to be coupled to mass spectrometry to identify the proteins. In this work, we describe the application of multidimensional liquid chromatography, SCX-RP-LC as well as SAX-RP-LC, coupled to electrospray ion trap mass spectrometry. Tryptic digested ribosomes were separated by ion exchange chromatography manually collected and prepared for reversed phase chromatography to analyze the peptides via nano-ESI mass spectrometry. The total numbers of identified proteins are compared in consideration of the separation method (SCX-RP versus SAX-RP). 相似文献
998.
999.
We investigated to what an extent mixed crystals of phosphates (arsenates) of Mn and Cd, [M5(HPO4)2(PO4)2 · 4 H2O], with Fe(II), Co, Ni, Zn and Cu can be formed. 相似文献
1000.