Fällungen in Gallerten

Ohne Zusammenfassung     

Kinematographische Quellungsanalyse im Dunkelfeld unter Verwendung des Mikromanipulators. I

Ohne Zusammenfassung über diese Untersuchung wurde bei gleich-, zeitiger Vorführung des Kinofilmes am 18. 3. 1933 von K. He? vor der kolloidchemischen Sektion der holl?ndischen chemischen Gesellschaft, am 15. 5. 1933 im Colloquium des Kaiser-Wilhelm-Institut für physikalische Chemie und Elektrochemie, sowie am 10. 7. 1933 in der Juli-Sitzung der Deutschen chemischen Gesellschaft berichtet. Für die überlassung optischer Instrumente zur Durchführung der Untersuchungen im Dunkelfeld sind wir der Deutschen Gemeinschaft zur Erhaltung und F?rderung der Forschung zu aufrichtigem Dank verpflichtet. Der I. G. Farbenindustrie A. G. und im besonderen Herrn Direktor Dr. Gajewski danken wir für die überlassung von Filmmaterial für die Kinoaufnahme.     

The electron impact-induced fragmentation of perchlorylbenzene

The modes of fragmentation of perchlorylbenzene (C₆H₅ClO₃) and its perdeutero derivative under electron impact are reported and discussed. The occurrence of the [C₆H₅O]^? and [C₆H₅O]⁺ ions is accounted for in terms of a novel phenyl migration from chlorine to oxygen.     

Antiprotozoal 6-substituted-5,6-dihydro-alpha-pyrones from Raimondia cf. monoica

Dichloromethane extracts of both the roots and the leaves of Raimondia cf. monoica showed in vitro antiplasmodial and leishmanicidal activities against Plasmodium falciparum and Leishmania panamensis, respectively. Three 6-substituted 5,6-dihydro-2H-pyran-2-ones were isolated. (1) and (2) were identified as (6S)-(5'-oxohepten-1'E,3'E-dienyl)-5,6-dihydro-2H-pyran-2-one (1) and (6R)-(5'-oxohepten-1'Z,3'E-dienyl)-5,6-dihydro-2H-pyran-2-one (2), respectively. (-)-Arentilactone (3) was also isolated. The structure of the new compound (1) was determined by spectroscopic methods; additional spectroscopic data for (2) are reported for the first time.     

Functional and structural characterization of ovine ornithine transcarbamoylase

Ornithine transcarbamoylase from ovine liver has been purified to homogeneity. Like all anabolic OTCs, the ovine enzyme is a trimer, constituted by identical subunits of 34 kDa. Sequence analysis of the 54 N-terminal residues of ovine OTC shows a high degree of homology with the human enzyme. The optimum pH and the Michaelis constants for the catalytic reaction were determined. The ovine enzyme is the most thermostable one among mammals OTCs, its critical temperature being 6 degrees C higher than those measured for the other enzymes. The enzyme has been crystallised and the structure determined at 3.5 A resolution. Crystals belong to the cubic P4(3)32 space group, with a = b = c = 184.7 A and a solvent content of about 80%. There is no evidence of any ligand in the active site cavity, indicating that the crystals contain an unliganded or T state of the enzyme. The unliganded OTCase enzyme adopts a trimeric structure which, in the crystal, presents a three-fold axis coincident with the crystallographic one. The conformation of each monomer in the trimer is quite similar to that of the liganded human protein, with the exception of a few loops, directly interacting with the substrate(s), which are able to induce a rearrangement of the quaternary organisation of the trimer, that accounts for the cooperative behaviour of the enzyme following the binding of the substrates.     

Diastereoselective addition of γ-alkylthio-allylboronates to aldehydes

The Z- and E-γ-alkylthio-allylboronates $\text{5}$ and $\text{10}$ were found to add aldehydes forming diastereoselectively the adducts $\text{7}$ and $\text{6}$ respectively in high yield.     

Conformational analysis of new 14-membered ring diketal dilactam macrocycles: molecular mechanics, liquid and solid state NMR studies

A conformational study of new diversely substituted 14-membered diketal dilactam macrocycles was conducted by NMR spectroscopy in liquid and solid states, molecular mechanics calculations and, for one compound, a previous X-ray analysis. The results obtained by the different techniques show that the conformations depend closely on whether the molecules are chiral or achiral and on the stereochemistry of the ketal OMe groups. In achiral compounds, the most stable conformation of each compound has, in both the liquid and solid states, the two NH-CO links positioned perpendicular to the macrocycle plane, lending to the trans-7,7′-OMe macrocycles 6b and 7b a rectangular [3434]-type structure. In contrast, in chiral compounds, the most stable conformations are not the same in the liquid and solid phases. In the liquid state the conformations are set by the presence of one or two N₄-H?O_1′, N_4′-H?O₁ intramolecular hydrogen bonds that position the amide group parallel to the macrocycle plane, whereas in the solid state the amide moieties again adopt a perpendicular position which can be stabilized, when the 3-R substituent is not too bulky, by intermolecular N-H?OC bonds between parallel sheets, and exceptionally, in the cis-7,7′-OMe-3,3′-Ph compound 1c, by a π-π stacking effect between the phenyl groups.     

Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6-Oxo-isophoron. VI. Synthese Von Rhodoxanthin und (3-RS, 3′RS)-Zeaxanthin; Zugänge zur C15-Ringkomponente über 3-Oxo-jonon-Derivate

Technical Procedures for the Synthesis of Carotenoids and Related Compounds from 6-Oxo-isophorone, VI. Synthesis of Rhodoxanthin and (3RS, 3′RS)-Zeaxanthin; Routes to the C₁₅-Ring Component via 3-Oxo-ionone Derivatives The C₁₅-ring component 4 , key intermediate of a new scheme for the synthesis of rhodoxanthin ( 1 ) and (3RS, 3RS)-zeaxanthin ( 3 ), has been synthesized starting from 6-oxo-isophorone ( 7 ) via 3-oxo-cyclocitral and 3-oxo-ionone derivatives.