Carbocyclische Verbindungen aus Monosacchariden. I. Umsetzungen in der glucosereihe

Carbocyclic Compounds from Monosaccharides. 1. Transformations in the Glucose Series A method for the preparation of pentasubstituted cyclopentanes from monosaccharides is presented, involving two crucial steps, viz. the reductive fragmentation of 5-bromo-5-deoxyglucosides (such as 10, 17 and 23 , see Scheme 3) with Zn or butyl lithium yielding 5,6-dideoxy-hex-5-enoses (such as 11 and 24 , see Schemes 3 and 4), and the subsequent cyclization of these hexenoses with N-methyl- or N-(alkoxyalkyl)hydroxylamines (via the corresponding nitrones) to form cyclopentano-isoxazolidines (see Scheme 2). Thus, the glucosides 17 and 23 were converted diastereoselectively and in good yields into the cyclopentano-isoxazolidines 27 and 45 (Schemes 5 and 7), which were characterized by their transformation into various derivatives. 27 and 45 were correlated through the common derivative 62 . The configuration of the cyclization products were established by pyrolysis of the N-oxide 65 to the enol ether 67 (Scheme 10).     

Carbocyclen aus Monosacchariden. III. Zur Diastereoselektivität der Bildung von Cyclopentanderivaten. Umsetzungen in der Galactosereihe

Carbocycles from monosaccharides. III. Concerning the diastereoselective formation of cyclopentane derivatives. Transformations in the galactose series. The diastereoselectivity of the intramolecular nitrone-olefine cycloaddition of 1 , 3 and 4 (Scheme 1), yielding only 2 , 5 and 6 but none of the isomers 8 , 9 and 10 is explained by assuming a kinetic control and postulating that the relative activation energies of the two relevant transition states in the cyclization of e.g. 1 can be estimated from the conformers A and B , the latter being destabilized by a synperiplanar arrangement of the nitrone function and the 2-alkoxy-group (Scheme 2). It is further postulated, that this destabilization is responsible for the formation of (2,3)-trans configurated products. Since 2 , 5 and 6 are presumably thermodynamically more stable than 8 , 9 and 10 , a case was investigated, where the cycloaddition can either give thermodynamically less stable (2,3)-trans-product such as 12 or a thermodynamically more stable (2,3)-cis-product such as 13. 12 and 13 could both be formed from the aldehyde 25 via the nitrone 11 (Schemes 3 and 5). Treatment of the galactoside 16 first with Zn in aqueous butanol (forming among other products 25 and its 2-debenzyl-oxy-derivative) and then with N-Methyldroxylamine yielded the isoxazolidines 12 (72%), 13 (2%) and 27 (7%) (Schemes 4 and 6). Similarily, the anomeric silylated galactosides 17 and 23 gave 29 (78% from 17 , 77% from 23 ) and 27 (5% and 3%). Upon desilylation, 29 gave 32 , which was converted into 12 . The structure of the isoxazolidines was unambiguously deduced from their NMR. spectra and those of their derivatives 33 and 34 . Compound 32 was further transformed into its deoxyderivative 36 . The high diastereoselectivity of the cycloaddition restricts the number of diastereomeric, pentasubstituted cyclopentanes available by this method. However, cyclization of the 2-Hydroxy-aldehyde 37 (Scheme 8) gave the kinetically less favoured isomer 40 in a higher proportion, showing the differential influence of hydrogen-bonds on the relevant activation energies. Thermolysis of 32 gave 40 (79%) and 41 (11%). The structure of 41 was deduced from its NMR. spectra and those of its derivatives 42 and 43 . Thermolysis of 29 gave, after desilylation, 41 (42%), 40 (22%) and 32 (13%) and thermolysis of 6 lead to a 25 : 75 equilibrium with 44 (combined yield 90%). These transformations illustrate means leading to additional isomers and are in agreement with the proposed explanation of the diastereoselectivity in question.     

Die Massenspektren weiterer Verbindungen aus der Pyrolyse von Methylchlorsilanen

Zusammenfassung Die Massenspektren vom Si-Hexamethyldisilylmethylen und Si-Hexamethylcyclocarbosilan sowie ihrer hydrierten Produkte werden diskutiert. Die charakteristischen Bruchstückionen (P-15) und (P-1) gestatten die eindeutige Zuordnung der Molekulargewichte.

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Summary The mass spectra of the linear silicon-methylene compound [(CH₃)₃Si]₂CH₂ and of the cyclic compound Si₃(CH₂)₃(CH₃)₆ (6-ring) as well as their hydrogenated products up to (H₃Si)₂CH₂ and Si₃(CH₂)₃H₆ are given and discussed. The characteristic fragments ion (p-15) and (p-1) allow the unequivocal coordination to the molecular weights of the components.

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Der Deutschen Forschungsgemeinschaft und dem Land Nordrhein-Westfalen danken wir für die Förderung unserer Untersuchungen.     

Bildung und Eigenschaften von Acylphosphinen. II. Verbindungen aus der Reaktion von Tris(trimethylsilyl)phosphin mit Pivaloylchlorid

Syntheses and Properties of Acylphosphines. II. Compounds from the Reaction of Tris(trimethylsilyl)phosphine with Pivaloyl Chloride Tris(trimethylsilyl)phosphine reacts with pivaloyl chloride at +20°C in cyclopentane to form the enol form of pivaloylbis(trimethylsilyl)phosphine. In this compound one trimethylsilyl group is bound to phosphorus, the other to oxygen. As the n.m.r. spectra of the reaction at ?10°C in monoglyme show the thermally instable keto form with two trimethylsilyl groups bound to phosphorus is formed first and rearranges at slightly elevated temperatures. Substitution of the second trimethylsilyl group yields the enol form of dipivaloyltrimethylsilylphosphine. Tripivaloylphosphine with three acyl groups bound to phosphorus and the enol form of tert. butylpivaloyltrimethyl-silylphosphine are produced in side reactions.     

Bemerkenswerte Umsetzungen in der Dicyclopentadienreihe

-Dicyclopentadien wie Dihydro--dicyclopentadien werden mit Peressigsäure in Eisessig ausschließlich in die entsprechenden Oxidoverbindungen übergeführt, es unterbleibt also auffallenderweise die Acetolyse als Folgereaktion.Darstellung von Tetrahydro--dicylopentadien-on-(3) durch Isomerisierung von Dihydro--dicyclopentadienoxyd mittels Magnesiumbromid in absolut ätherischer Lösung.

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Herrn Prof. Dr.A. Franke zum 80. Geburtstag als Zeichen meiner Dankbarkeit und Verehrung gewidmet.     

Zum papierchromatographischen Nachweis von substituierten Hydrazinderivaten von Monosacchariden und verwandten Verbindungen

Ohne Zusammenfassung     

Verbindungen der L-Ascorbinsäure mit Metallen. II. Titanylascorbate

Compounds of L-Ascorbic Acid with Metals. II. Titanyl Ascorbates The titanyl ascorbates TiO(C₆H₇O₆)₂ · 2 H₂O and TiO(OH)(C₆H₇O₆) the preparation of which has been described elsewhere are characterized by electronic, infrared, and ¹H-nmr spectra. From measurements of the H₃O⁺ concentration of aqueous solutions of both compounds a simple model for describing their protolytic behaviour is derived.     

Automatische Analyse der fluorimetrisch bestimmbaren Verbindungen aus dem Katecholamin-Stoffwechsel mit einem Reaktionssystem

Zusammenfassung Es werden die optimalen Bedingungen für die automatisch-fluorimetrische Bestimmung folgender Verbindungen aus dem Katecholamin-Stoff-wechsel mitgeteilt: Dopa, Dopamin, Noradrenalin, Adrenalin, 3-Methoxytyramin, Normetanephrin, Metanephrin und Homovanillinsäure. Die Bestimmungen können mit einem einfachen Reaktionssystem durch Veränderung der chemischen und physikalischen Bedingungen im Analysenautomaten durchgeführt werden. Die sehr empfindliche fluorimetrische Analyse im Nanogrammbereich beruht auf der Oxidation der einzelnen Verbindungen und anschließenden Umwandlung der Zwischenprodukte in Fluorophore.

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Automatic analysis of the fluorimetrically determinable compounds from the catecholamine metabolism with one reaction system

Summary Optimal conditions are reported for the following compounds: dopa, dopamine, noradrenaline, adrenaline, 3-methoxytyramine, normetanephrine, metanephrine, homovanillic acid. The determinations are realized in one simple reaction system with the variation of chemical and physical system. The very sensitive fluorimetric analysis in the nanogram range is based on the oxidation of the single compounds and the following change of the intermediate products into fluorophores.

     

Bei der quantitativen Bestimmung von Monosacchariden auf Papierchromatogrammen

Ohne Zusammenfassung     

Verbindungen der Edelgase

Ohne Zusammenfassung     

Die Kristallstruktur der Hexagonalen Verbindungen BaMeIISbO9. II. Ba3CuSb2O9

Crystal Structure of the Hexagonal Compounds Ba^II₃Me^IISb^v₂O₉. II. Ba₃CuSb₂O₉ The crystal structure of the compound Ba₃CuSb₂O₉ was determined from single crystal X-ray diffraction data and refined down to R = 0.03. Ba₃CuSb₂O₉ crystallizes in the hexagonal space group P6₃mc (C) with a = b = 5.809 Å, C = 14.321 Å and Z = 2. The structure can be described by close–packed BaO₃ layers in the sequence cchcchcch…?(hex. BaTiO₃ type). Groups of two octahedra with common faces are connected by SbO₆ octahedra via common corners. They are occupied alternately by Cu and Sb. In agreement with the EPR spectra the CuO₆-octahedra present no static Jahn-Teller distortion at room temperature. However the thermal ellipsoids of the oxygen atoms indicate the presence of adynamic Jahn-Teller-effect.