Chlorsulfonierung von Aromaten mittels Malonsäurediamid-N,N′-disulfochloriden

Zusammenfassung Die Malonsäurediamid-N,N-disulfochloride1–4 übertragen beim Erhitzen in Benzol oder Toluol die SO₂Cl-Gruppe auf den Aromaten, wobei das Diamiddisulfochlorid in gasförmige Bruchstücke zerfällt. Das Massenspektrum von Isopropylmalonsäurediamid-N,N-disulfochlorid (1) wird diskutiert.

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Chlorosulfonation of aromatic hydrocarbons by means of malondiamide disulfochlorides

Malonamide-N,N-disulfochlorides (1–4) transfer their SO₂Cl-group to aromatic solvents if heated to reflux. Under these conditions the malonamide-N,N-disulfochlorides are cleaved into gaseous fragments. The mass spectrum of isopropylmalonamide-N,N-disulfochloride (1) is discussed.

     

Column chromatographic prefractionation leads to the detection of 543 different gene products in human fetal brain

In a previous publication a large series of proteins were identified in fetal human brain by the use of two-dimensional electrophoresis (2-DE) with subsequent matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and MALDI-tandem time-of-flight (TOF/TOF) analysis. Further identification of many more different spots by traditional 2-DE without additional step such as narrow immobilized ph gradient (IPG) strips or prefractionation seems unlikely and we therefore decided to separate extracted brain proteins by ion-exchange chromatography using a TSK gel DEAE-5PW column followed by 2-DE of individual fractions and analysis by MALDI-TOF/TOF with LIFT technology in fetal brain of the early second trimester. About 1880 protein spots corresponding to 543 different gene products were identified. These proteins included housekeeping, signaling, cytoskeletal, metabolic, antioxidant, and neuron/synaptosomal specific proteins. Among these, 314 gene products (314/543, 57.8%), which have never been detected in traditional 2-DE of human fetal brain, were observed by this method. This updated map of fetal brain proteins may serve as data base and reference map for fetal brain proteins, and the methodology applied may be used as a valuable analytical tool for the basis of protein expressional studies in health and disease.     

CHARACTERIZATION OF A MICROSECOND INTERMEDIATE IN THE LASER FLASH PHOTOLYSIS OF SMALL PHYTOCHROME FROM OAT

Abstract— Irradiation of small phytochrome from oat in its P_r form with 15 ns laser pulses of different wavelengths(605–655 nm) gave rise to a difference absorption with maxima at 400 and 685 nm for the first detectable transient. Bleaching of a 660 nm band was observed, non-recuperable up to 1 ms. The transient absorption has a lifetime of 70±15 μs at 273 K. The transient is tentatively identified as lumi-R and the conformation of its chromophore is postulated to be more extended than that of P_r. A deviation from the exponential decay of the lumi-R absorption at 284 and 300 K and the lack of observable enhancement of the far-red absorption within 1 ms are interpreted in terms of the appearance of still other intermediates on this time scale between lumi-R and P_fr phytochrome.     

A Flexible Stereoselective Synthesis of the Spirosesquiterpenes (±)-β-Acorenol, (±)-β-Acoradiene, (±)-Acorenone-B and (±)-Acorenone via an Intramolecular Ene-Reaction

The racemic spirosesquiterpenes β-acorenol ( 1 ), β-acoradiene ( 2 ), acorenone-B ( 3 ) and acorenone ( 4 ) (Scheme 2) have been synthesized in a simple, flexible and highly stereoselective manner from the ester 5 . The key step (Schemes 3 and 4), an intramolecular thermal ene reaction of the 1,6-diene 6 , proceeded with 100% endo-selectivity to give the separable and interconvertible epimers 7a and 7b . Transformation of the ‘trans’-ester 7a to (±)- 1 and (±)- 2 via the enone 9 (Scheme 5) involved either a thermal retro-ene reaction 10 → 12 or, alternatively, an acid-catalysed elimination 11 → 13 + 14 followed by conversion to the 2-propanols 16 and 17 and their reduction with sodium in ammonia into 1 which was then dehydrated to 2 . The conversion of the ‘cis’-ester 7b to either 3 (Scheme 6) or 4 (Scheme 7) was accomplished by transforming firstly the carbethoxy group to an isopropyl group via 7b → 18 → 19 → 20 , oxidation of 20 to 21 , then alkylative 1,2-enone transposition 21 → 22 → 23 → 3 . By regioselective hydroboration and oxidation, the same precursor 20 gave a single ketone 25 which was subjected to the regioselective sulfenylation-alkylation-desulfenylation sequence 25 → 26 → 27 → 4 .     

29Si-NMR-Untersuchungen an einigen Cyclosilanderivaten

²⁹Si-NMR spectras of some new cyclosilane derivatives were measured. First aspects of the dependence of chemical shift on ring size and kind of substituents are given.

     

Spaltungen mittels Diazoniumverbindungen und Chinonimidchlorid, 6. Mitt.: Über Hydroxychalkone

Zusammenfassung Es wird über die Reaktion verschieden methylsubstituierter 4-Hydroxychalkone mittels Chinonimidchlorid berichtet und gezeigt, daß die Ausbeute an 2,6-Dimethylphenol-indophenol bei der Spaltung von 4,4-Dihydroxy-3,5,3-trimethylchalkon (VII) am RingB dreimal so groß ist als beim 4,4-Dihydroxy-3,3,5-trimethylchalkon (III) am RingA.

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The reaction between several methyl-4-hydroxy-chalkones and p-benzoquinone-monochloroimine has been studied. It has been shown that the yield of 2.6-dimethylphenol-indophenol from the cleavage of 4.4-dihydroxy-3.5.3-trimethyl-chalkon (VII) at ringB is three times the yield resulting from the cleavage of 4.4-dihydroxy-3.3.5-trimethylchalkon (III) at ringA.

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Herrn Prof. Dr.H. Bretschneider zum 60. Geburtstag gewidmet.     

Phosphaniminato-Komplexe des Schwefels. Synthese und Kristallstrukturen von [O3SS(NPPh3)2] · CH3CN, [SO(NPPh3)2] und [SCl(NPMe3)2]Cl

Phosphorane Iminato Complexes of Sulfur. Syntheses and Crystal Structures of [O₃SS(NPPh₃)₂] · CH₃CN, [SO(NPPh₃)₂], and [SCl(NPMe₃)₂]Cl The title compounds have been prepared by the reaction of Me₃SiNPPh₃ with SO₂ and SOCl₂, respectively, and by the reaction of Me₃SiNPMe₃ with S₂Cl₂. They form colourless, moisture sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. [O₃SS((NPPh₃)₂)] · CH₃CN : Space group Pca2₁, Z = 4, structure solution with 4016 observed unique reflections, R = 0.050. Lattice dimensions at ?60°C: a = 1865.1, b = 1168.4, c = 1569.0 pm. The compound has a zwitterionic structure with a S? S bond length of 218.2 pm and bond lengths S? N of 161.2 and P? N of 160.1 pm. [SO(NPPh₃)₂] : Space group P2₁/c, Z = 4, structure solution with 2854 observed unique reflections, R = 0.113. Lattice dimensions at ?50°C: a = 1173.1, b = 1585.6, c = 1619.2 pm, b? = 98.13°. The compound forms monomeric molecules, in which the positions of S and N atoms are disordered in two positions. The bond lengths are S? N 166 pm and P? N 163 pm in average. [SCl(NPMe₃)₂]Cl : Space group P1 , Z = 2, structure solution with 2416 observed unique reflections, R = 0.038. Lattice dimensions at 20°C: a = 613.2, b = 1030.3, c = 1111.4 pm, α = 88.48°, b? = 88.01°, γ = 83.10°. The compound forms ions [SCl(NPMe₃)₂]⁺ and Cl^?. In the cation the sulfur atom is ?-tetrahedrally coordinated with a long S? Cl distance of 246.9 pm and bond lengths S? N of 155.3 pm and P? N of 164.3 pm in average.     

Contribution à la phytochimie du genre Gentiana,XIX. Identification de nouveaux C-glucosides flavoniques dans Gentiana pyrenaicaL

Phytochemistry of genus Gentiana, XIX: Identification of new C-glycosylflavones in Gentiana pyrenaica L . Five flavone C-glucosides [6-C-β-D -glucopyranosyl-tricine ( 1 ) or isopyrenine; 7-O-β-D -glucopyranosyl-6-C-β-D -glucopyranosyltricine ( 2 ) or isopyrenine-7-O-glucoside; isoscoparine-7-O-glucoside ( 3 ); 7-O-β-D -glucopyranosyl-6-C-β-D -glucopyranosylacacetine ( 4 ) and isovitexine-7-O-glucoside ( 5 ) or saponarine] as well as the flavonol glucoside isoquercitrine ( 9 ) have been isolated chromatographically, using polyamide and cellulose columns, from the aerial parts of Gentiana pyrenaica L . 1 and 2 are new compounds and the first glycoflavones trisubstituted on cycle B. Compound 4 is also encountered for the first time in nature.     

Study of recombination of photocarriers in a-As2Se3 and As2Te3 by photoconductivity and photo-absorption measurements

Time-dependent photoconductivity and photo-absorption measurements, the latter using probe beams of 0.1 eV and 1.4 eV, were analyzed on the basis of a saturated band tail model. By a best fit procedure of theory to experiment band structure and recombination parameters for a-As₂Se₃ were obtained.