Gilmaniellin and Dechlorogilmaniellin,Two Novel Dimeric Oxaphenalenones

The structure and configuration of gilmaniellin, a metabolite of Gilmaniella humicola BARRON , has been shown to be 2 by X-ray analysis. By comparison of spectral data structure 1 has been assigned to dechlorogilmaniellin.     

Identification of amber and imitations by near infrared reflection spectroscopy

Imitations of amber have been prepared since a long time, but the number of imitations is increasing since modern polymers are available. At present, many imitations are based on a few synthetic polymers and even experts have some problems in distinguishing between real and falsed amber without destruction of the material. IR-Spectroscopy or pyrolysis combined with gas chromatography/mass spectrometry are very efficient methods in identifying amber and imitations but these methods need a sample preparation. By means of near infrared reflection spectroscopy it is possible to identify amber and imitations without any sample preparation in a short time. Optimization of the method and the application are discussed.     

Detection of banned meat and bone meal in feedstuffs by near-infrared microscopic analysis of the dense sediment fraction

In this paper we present an alternative method for detection of meat and bone meal (MBM) in feedstuffs by near-infrared microscopic (NIRM) analysis of the particles in the sediment fraction (dense fraction (d >1.62) from dichloroethylene) of compound feeds. To apply this method the particles of the sediment fraction are spread on a sample holder and presented to the NIR microscope. By using the pointer of the microscope the infrared beam is focussed on each particle and the NIR spectrum (1112–2500 nm) is collected. This method can be used to detect the presence of MBM at concentrations as low as 0.05% mass fraction. When results from the NIRM method were compared with the classical microscopic method, a coefficient of determination (R²) of 0.87 was obtained. The results of this study demonstrated that this method could be proposed as a complementary tool for the detection of banned MBM in feedstuffs by reinforcement of the monitoring of feeds.     

Synthesen und chemisches Reaktionsverhalten neuer überbrückter Chinonderivate. Kupplungsreaktionen von Diazoniumsalzen mit 2-Methoxy-1,6-methano [10]annulen

Syntheses and Chemical Properties of New Bridged Quinone Derivatives. Coupling Reactions of Aryldiazonium Salts with 2-Methoxy-1,6-methano[10]annulene Coupling of 2-methoxy-1,6-methano[10]annulene (3) with the aryldiazonium salts 4a-4i yields the quinone hydrazones 5a-5i. The spectroscopic properties of these products are described. The reaction of 3 with 4-nitrophenyldiazonium tetrafluoroborate buffered with sodium acetate in dry methanol yielded after chromatographic separation the azo derivative 7 on the one hand and a mixture of the valence tautomers 8a and 8b on the other.     

BINAS - synthesis and use of a new ligand for propylene hydroformylation

BINAS is a new, very efficient ligand for propylene hydroformylation. BINAS is made by the sulfonation of NAPHOS. Different synthetic routes to NAPHOS are discussed. A new two step synthesis starting from 2,2′-bis(bromomethyl)-1,1′-binaphthyl is described.     

1H and 13C NMR signal assignment of cucurbitacin derivatives from Citrullus colocynthis (L.) Schrader and Ecballium elaterium L. (Cucurbitaceae)

2D NMR-derived 1H and 13C NMR signal assignments of six structurally closely related cucurbitacin derivatives are presented. The investigated 2-O-beta-D-glucopyranosylcucurbitacins I, J, K, and L were obtained from Citrullus colocynthis (L.) Schrader whereas the aglyca cucurbitacin E and I were isolated from Ecballium elaterium L.     

Differential Hydrogen Exchange During Biosynthesis of Cytochalasins B and D

Sodium [2-¹³C,2-²H₃]acetate was incorporated into cytochalasin B( 1 ) by Phoma exigua and into cytochalasin D ( 2 ) by Zygosporium masonii. The ¹³C-NMR. and ²H-NMR. of the metabolites showed that most of the deuterium was lost except at carbon atoms which are in polyketide chain-initiating units.     

Optisch aktive 3-Amino-2H-azirine als Bausteine für enantiomerenreine αα-disubstituierte α-Aminosäuren: Synthese von Isovalin-Synthonen und Einbau in ein Trichotoxin-A-50-Segment

Optically Active 3-Amino-2H-azirines as Synthons for Enantiomerically Pure αα-Disubstiuted α-Amino Acids: Syntheses of Isovaline Synthons and a Segment of Trichotoxin A-50 The synthesis of a novel 3-amino-2-methyl-2-[2-(phenylsulfonyl)ethyl]-2H-azirine derivative 12 with a chiral substituent at the amino group is described. Chromatographic separation of the diastereoisomer mixture gave pure diastereoisomers which, after an electrochemical cleavage of the phenylsulfonyl group, yielded the (S)- and (R)-isovalin (Iva) synthons 13a and 13b , respectively. The absolute configuration of the precursor molecule 12b was established by X-ray crystallography. The Iva synthons were successfully used in the synthesis of the C-terminal pentapeptide Z-Leu-Aib-(R)-Iva-Gln-Valol of the peptaibole Trichotoxin A-50 and its epimer.     

Analysis of lipoproteins with analytical capillary isotachophoresis

An analytical free flow capillary isotachophoresis procedure, with a discontinuous electrolyte system, for the detailed analysis of lipoproteins in human body fluids has been developed. The technique is based on prestaining whole serum lipoproteins with a lipophilic dye before separation. Human serum lipoproteins are separated into 14 well-characterized subfractions according to their electrophoretic mobility. High density lipoproteins (fraction 1 to 6) are separated into three major subpopulations, the fast migrating high density lipoprotein (HDL) subpopulation, containing mainly apo AI and phosphatidylcholine, the subpopulation with intermediate mobility, consisting of particles rich in apo AII, apo E, and C apolipoproteins, and the slowly migrating HDL subfraction, containing mainly particles rich in apo AI, apo AIV, and lecithin: cholesterol acyltransferase (LCAT) activity. The apo B containing lipoproteins (fraction 7 to 14) can be subdivided into four major functional groups. The first represents chylomicron derived particles and large triglyceride-rich very low density lipoproteins (VLDL). The second group consists of small VLDL and intermediate density lipoprotein (IDL) particles, anf the third and fourth group represent the low density lipoproteins. The isotachophoretic analysis of human serum samples obtained from patients with hyperlipoproteinemias is compatible with the classification according to the Frederickson phenotypes and reflects the respective biochemical abnormalities. Furthermore, several genetic disorders of lipid and lipoprotein metabolism like HDL deficiency syndromes, familial LCAT deficiency, Fish eye disease, hypobetalipoproteinemia and abetalipoproteinemia can be well characterized by analytical capillary iso tachophoresis. In addition to patient analysis we investigated the influence of lipid lowering drugs on the lipoprotein subfraction distribution during therapy with analytical capillary isotachophoresis.     

First successful reaction of a silyl anion with hafnium tetrachloride

Hafnium tetrachloride reacts with the tris(trimethylsilyl)silyl potassium tmen adduct (1) to form a [tris(trimethylsilyl)silyl]trichlorohafnium tmen complex (2); reaction of 2 with 2,6-dimethylphenylisonitrile leads to insertion into the silicon hafnium bond (4).