Aminosubstituierte 2-azoniaallenyliden-komplexe des chroms und wolframs

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.     

Preparation of both enantiomers of malic and citramalic acid and other hydroxysuccinic acid derivatives by stereospecific hydrations of cis or trans 2-butene-1,4-dioic acids with resting cells of Clostridium formicoaceticum

(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%.     

Multidimensional nano-HPLC for analysis of protein complexes

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).     

Bildung von Mischkristallen bei Verbindungen vom Huréaulith-Typ

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.     

Nitrostyrene Derivatives of Adenosine 5′-Glutarates as Selective Inhibitors of the Epidermal Growth Factor Receptor Protein Tyrosine Kinase

The syntheses and biological activities of some nitrostyrene derivatives of adenosine 5′-glutarates, a novel class of selective, bi-substrate-type inhibitors of the EGF receptor protein tyrosine kinase with IC₅₀ values around 1 μM . Only marginal inhibition of the tyrosine kinases v-able and c-src and of the serine/threonine kinase PKC was observed. Compounds 8, 9, 11 , and 12 – lacking the adenosine moiety – were ten times less active than the most potent derivatives, whereas 17 – lacking the nitrostyryl part – showed no inhibitory activity at all. Most of the compounds showed potent antiproliferative activity against an EGF-dependent mouse keratinocyte cell line.     

Darstellung und Konfiguration von Tricarbonylchromat-Anionen mit SnCl3− und GeCl3− als Liganden

B₃N₃Me₆Cr(CO)₃ reacts with [AsPh₄] [SnCl₃] and [AsPh₄] [GeCl₃] in tetrahydrofuran to give [AsPh₄]₃[Cr(CO)₃(SnCl₃)₃] and [AsPh₄]₃[Cr(CO)₃(GeCl₃)₃], respectively. According to IR. and ¹³C-NMR.-data, the tricarbonylate anions possess a meridional configuration. The donor-acceptor properties of SnCl₃^? and GeCl₃^? in the anions [Cr(CO)₃(ECl₃)₃]^3? (E = Sn, Ge) are very similar. A similar synthesis of [AsPh₄]₃[Cr(CO)₃(SnF₃)₃] was not successful.     

Derivate der 5,6-Dihydro-2H-pyran-3-carbonsäure

Summary Some derivatives of 5,6-dihydro-2H-pyran-3-carboxaldehyde (7) and of its oxidation product 5,6-dihydro-2H-pyran-3-carboxylic acid (8) have been prepared. The aldehyde derivatives as well as the amides and esters of8 have been tested in an insecticidal/fungicidal/acaricidal screening programme. The methylester35 shows a distinct knock down effect against the fruit flyDrosophila melanogaster.

     

Thin-layer chromatography and multivariate data analysis of willow bark extracts

In most cases the pharmacological activity of plant extracts is not assigned to single components and often not all active ingredients are known. Approaches other than those considering single compounds only to analyze plant material have proven helpful for a better characterization of extracts in their entirety. In this study extracts of willow bark are analyzed by high-performance thin-layer chromatography (HPTLC) and two different pharmacological tests [the 2,2'-azobis (2-amidinopropane) dihydrochloride reaction and the xanthine/xanthine oxidase reaction] with the help of multivariate data analysis. Described are two models using the results of the chromatographic study of 22 various extracts of willow bark and their pharmacological properties. The chromatographic data are obtained by a special TLC scanner that enables measurement of HPTLC tracks simultaneously in the range of lambda = 200-400 nm. Additionally, the developed models are used to predict the activity of another three extracts of willow bark demonstrating the quality of the model.