Published by De Gruyter

Volume 35 Issue 11

Issue of Zeitschrift für Naturforschung B

Contents
Journal Overview

Open Access June 2, 2014

Neue phosphororganische Liganden: 2-Pyridyl-phosphane, -phosphanmethylene und -phosphanborane / New Organophosphorus Ligands: 2-Pyridyl-phosphanes, -phosphanemethylenes, and -phosphaneboranes

Hubert Schmidbaur, Yoshio Inoguchi

Page range: 1329-1334

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Abstract

Diphenyl(2-pyridyl)phosphane, bis-2-pyridyl(phenyl)phosphane, and tris-2-pyridylphosphane (1a-c) are prepared from 2-pyridyl-lithium and the corresponding chlorophosphanes. These phosphanes can be converted into the methylene compounds via the methylphosphonium salts 2a-c. The ylids 3a-c and their precursors were characterized by a detailed 1 H, 13 C, and 31 P NMR study. 3 c is thermally unstable and undergoes a spontaneous condensation reaction. The three related phosphaneboranes 4a-c can be obtained in the reactions of 1 a - c with tetrahydrofuran-borane. The BH 3 groups are selectively bonded to the phosphorus atoms. - 1 c forms insoluble 1 : 1 complexes with CuCl and AgCl, but a soluble adduct with AuCl (5 c, 6 c, and 7 c, respectively). A similar AuCl complex is formed from (CO)AuCl and 1 a . In both gold compounds the ligands are solely P-bonded.

Open Access June 2, 2014

Über die Reaktion von Trifluorphosphin (PF₃), Difluormethylphosphit (F₂POCH₃) und Trimethylphosphit [P(OCH₃)₃] mit Aquacobalamin in Methanol / On the Reaction of Trifluorophosphine (PF₃), Difluoromethylphosphite (F₂POCH₃) and Trimethylphosphite [P(OCH₃)₃] with Aquacobalamin in Methanol

Rainer Bieganowski, Wilhelm Friedrich

Page range: 1335-1340

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Abstract

Aquacobalamin reacts with trifluorophosphine in methanol. The products, fluoromethylphosphito- P-cobalamin and dimethylphosphito-P-cobalamin, were identified and characterized by means of electrophoresis, NMR ( 1 H, 31 P, 19 F) and X-ray structure analysis. Both cobalamins were synthesized in a similar way using difluoromethylphosphite and trimethylphosphite as reagents. Fluoromethylphosphito-P-cobalamin is much less soluble in water than cyanocobalamin. Dimethylphosphito-P-cobalamin is lightsensitive. Both cobalamins crystallize from water and methanol/water.

Open Access June 2, 2014

Zur Kenntnis farbiger ternärer und quaternärer Zintl-Phasen / Coloured Ternary and Quaternary Zintl-Phases

Ursula Eberz, Werner Seelentag, Hans-Uwe Schuster

Page range: 1341-1343

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Abstract

Ternary and quaternary, mostly coloured compounds of Au, Pd and Pt, resp., with Li, Mg, Sc and Sn were prepared and structurally investigated. They crystallize in a "filled" Zinkblende type structure (space group F?3m) and can be characterized as ternary or quaternary Zintl-phases. Colours seem to depend on unfilled d-orbitals of Au, Pd or Pt.

Open Access June 2, 2014

Struktur und Eigenschaften des Kaliumhydrogendiarsenit-Hemihydrats, KHAs₂O₄ · 1/2 H₂O / Structure and Properties of the Potassiumhydrogendiarsenite-hemihydrate, KHAs₂O₄ · 1/2 H₂O

Joachim Fuchs, Hernan Guevara

Page range: 1344-1348

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Abstract

KHAs 2 O 4 · 1/2 H 2 O crystallizes in the tetragonal space group I 4/m with the lattice constants a = 14,480 Å, c = 5,250 Å. The anion forms infinite chains, [HAs 2 O 4 ] n n- , in the direction of the c axis. Arsenic is surrounded by three oxygens in trigonal pyramidal co-ordinations. Ultracentrifuge work shows that the solution contains monomeric species, probably [ASO(OH) 2 ] - . Raman spectra gave no evidence for the existence of As-H-bonds either in the solid or in solution.

Open Access June 2, 2014

Spektroskopische Untersuchungen in der Festkörperchemie, XIII. Temperaturabhängigkeit der ¹²⁷I-Kernquadrupolkopplung in NH₄IO₄ und anderen Periodaten / Spectroscopic Investigations in the Solid State Chemistry, XIII. Temperature Dependence of the ¹²⁷I-Nuclear Quadrupole Coupling in NH₄IO₄ and other Periodates

Paul K. Burkert

Page range: 1349-1354

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Abstract

The temperature dependence of the electric field gradients was measured by I. and II. order quadrupole effects of the 127 I NMR signals in scheelite-structured NH 4 IO 4 and RbIO 4 , in pseudo-scheelite CsIO 4 and in N(CH 3 ) 4 IO 4 , where r cation > r anion - An interpretation of the anomalous positive temperature dependences of the quadrupole coupling constants in NH 4 IO 4 and in the isostructural NH 4 ReO 4 is proposed.

Open Access June 2, 2014

Darstellung und Charakterisierung der Tetrabutylammoniumsalze der Tetrahalogenooxotechnetate(V), [TcOCl₄]^- und [TcOBr₄]^- / Preparation and Characterization of the Tetrabutylammonium Salts of the Tetrahalooxotechnetates(V), [TcOCl₄]^- and [TcOBr₄]^-

W. Preetz, G. Peters

Page range: 1355-1358

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Abstract

The treatment of (TBA)TcO 4 with conc. HCl or HBr at room temperature yields (TBA)[TcOCl 4 ] or (TBA)[TcOBr 4 ], which are nearly insoluble in acidic aqueous solutions, but well soluble in organic solvents. The vibrational spectra indicate C 4v symmetry for the complex ions. (TBA)[TcOBr 4 ] shows an unusual resonance Raman effect, as the progression of overtones runs with the B 1 TcCL 4 stretching vibration instead of the symmetric A 1 mode. The coupling of B 1 with the first overtone of νTcO gives more intense difference than combination bands.

Open Access June 2, 2014

Ringkontraktion am Cyclotrisilazan -System - Synthese und Molekülstrukturen zweifach silylverknüpfter Cyclodisilazane / Ring Contraction in the Cyclotrisilazane System - Synthesis and Molecular Structures of Silyl-Bridged Cyclodisilazanes

William Clegg, Michael Hesse, Uwe Klingebiel, George M. Sheldrick, Lutz Skoda

Page range: 1359-1365

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Abstract

l-(Fluorodiorganylsilyl)-2,2,4,4,6,6-hexamethyl-3-(trimethylsilyl)cyclotrisilazanes react with butyllithium to give the corresponding lithium salts. Ring contraction of the lithium salts with formation of lithiated (fluorodiorganylsilyl)amino-substituted four-membered rings is observed in THF solution. The dimerisation of these cyclodisilazanes with elimination of LiF is demonstrated by crystal structure determinations of three products. Monoclinic and triclinic crystalline modifications of one compound could be isolated.

Open Access June 2, 2014

Über zwei Modifikationen von "Tl₂Cl₃"-valenzgemischten Thallium(I)-hexahalogenothallaten(III) Tl₃ [TlCl₆] / On Two Modifications of "Tl₂Cl₃"-Mixed Valence Thallium(I)-hexahalogenothallates(III)

Reinhild Böhme, Jörg Rath, Bernd Grunwald, Gerhard Thiele

Page range: 1366-1372

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Abstract

The mixed valence thallium chloride "Tl 2 Cl 3 " is polymorphous. Raman spectra and comparable lattice translations suggest similar structures of both modifications. The crystal structure of the rhombic α-Tl 2 Cl 3 crystallizing in yellow, needle-shaped crystals, has been determined from three-dimensional X-ray diffraction data. The unit cell with cell parameters a= 1474.8(5) pm, b - 2508.7(6) pm and c = 1267.6(2) pm contains 16 formula units distributed on 24 independent atom positions. The compound is a mixed valence thallium(I)-hexachlorothallate(III) Tl 3 [TlCl 6 ] because three of the nine independent Tl atoms are surrounded octahedrally by CI atoms in distances of 250-265 pm, while the other Tl atoms have seven, eight or nine CI neighbours variing between 306 and 383 pm. β-Tl 3 [TlCl 6 ] forms pale yellow thin platelets and crystallizes monoclinic with cell parameters a = 2549.4(13) pm, 6 = 1469.9(8) pm, c = 1308.5(12) pm and β = 108.58°.

Open Access June 2, 2014

Darstellung, Eigenschaften und Kristallstruktur von 6-Methyl-4-Methylen-2-Phenyl-4 H-1.3.2-dioxaphosphorin / Preparation, Properties and Crystal Data of 6-Methyl-4-methylen-2-phenyl-4 H-1,3,2-dioxaphosphorin

J. v. Seyerl, G. Huttner

Page range: 1373-1375

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Abstract

PPh(C 6 H 5 O 2 ) was prepared for the first time in the free state. The compound crystallizes in the monoclinic spacegroup P2 1 /c; a= 1084, b= 1079, c= 989 pm; β= 113.7°.

Open Access June 2, 2014

Darstellung von (Trimethylsilylmetliyl)gallium-Verbindungen / Preparation of (Trimethylsilylmethyl)gallium Compounds

Klaus-Dieter Fuhrmann, Friedo Huber

Page range: 1376-1377

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Abstract

(Me 3 SiCH 2 ) 3 Ga, a monomer in benzene solution and a rather weak Lewis acid, was prepared from GaCl 3 and Me 3 SiCH 2 MgCl in Et 2 O (Me = CH 3 , Et = C 2 H 5 ). Et 2 GaCH 2 I, obtained from Et 2 GaI and CH 2 N 2 , reacts with Me 3 SiMgCl in Et 2 O to give a solution of Et 2 GaCH 2 SiMe 3 . This compound and PPh 3 form the more stable complex Et 2 GaCH 2 SiMe 3 · PPh 3 (Ph = C 6 H 5 ), which can be isolated.

Open Access June 2, 2014

X-ray Structural Analyses of Two Allotropes of Cycloheptasulfur ( γ and δ-S₇ ) [1]

Ralf Steudel, Jürgen Steidel, Joachim Pickardt, Fritz Schuster, Richard Reinhardt

Page range: 1378-1383

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Abstract

X-ray structural analyses of two monoclinic allotropes of cycloheptasulfur carried out at -110 °C revealed almost identical chair-like molecular structures of approximate Cs symmetry with bond distances between 199.5 and 218.2 pm, bond angles between 101.5 and 107.5°, and torsional angles between 0 and 109°.

Open Access June 2, 2014

4(4-Alkyloxybenzoyloxy)-4' -cyanoazobenzole: Eine homologe Reihe flüssigkristalliner Verbindungen mit der ungewöhnlichen Phasenfolge smektisch A-nematisch-smektisch A / 4(4-Alkyloxybenzoyloxy)-4'-cyanoazobenzenes: A Homologous Series of Liquid Crystals Exhibiting the Unusual Phase Sequence Smectic A -Nematic -Smectic A

Gerd Heppke, Reinhard Hopf, Bernd Kohne, Klaus Praefcke

Page range: 1384-1388

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Abstract

The synthesis and the phase transition temperatures of homologous liquid crystalline 4(4-alkyloxybenzoyloxy)-4'-cyanoazobenzenes with alkyl chain length n = 1-12 and n = 16 are reported. All compounds exhibit smectic A phases; the S A phase region being interrupted by a "re-entrant" nematic phase for alkyl chain lengath n ≥ 9.

Open Access June 2, 2014

O.O-Diphenyl-N-chloramidophosphat / 0,0-Diphenyl-N-chlorophosphoramidate

Kurt Drewelies, Volker Münch, Jochen Jander, Hans Peter Latscha

Page range: 1389-1390

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Abstract

(C 6 H 5 O) 2 P(O)NHCl can be synthesized in 83-88% yield by direct hydrolysis of (C 6 H 5 O) 2 P(O)NCl 2 in petroleumether solution. This first example of a new class of N-halogeno compounds, a colourless crystalline substance was characterized by 31 P and 1 H NMR, IR and mass spectroscopy as well as by elemental analysis.

Open Access June 2, 2014

Arsenverbrückte zweikernige Mn(CO)₄Br-Komplexe / Arsenic Bridged Dinuclear Mn(CO)₄Br Complexes

Michael Börner, Rainer Müller, Heimich Vahrenkamp

Page range: 1391-1394

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Abstract

In Mn(CO) 5 Br one or two CO groups could be replaced by Me 2 AsCl. From Me 2 AsCl-Mn(CO) 4 Br with carbonyl metalates, or from Mn(CO) 5 Br with organometal dimethylarsenides, the arsenic bridged dinuclear complexes L n M-AsMe 2 -Mn(CO) 4 Br with L n M = CrCp(CO) 3 , MoCp(CO) 3 , WCp(CO) 3 , and Mn(CO) 5 were obtained. Upon attempts to convert these to metal-metal bonded compounds the Cr-As-Mn complex decomposed whereas the Mn-As-Mn complex was spontaneously converted to (CO) 4 Mn[μ-AsMe 2 , μ-Br]Mn(CO) 4 .

Open Access June 2, 2014

Synthesis of Some Diazepinones, Oxazepinones, Pyrimidoquinazolinones and Related Compounds from 1,4-Bis(ethoxycarbonyl)-2,5-diamino-1,4-cyclohexadiene

Fathy A. Amer, El-Sayed Afsah, Mohamed A. Metwally, Mohamed T. El-Zimaity

Page range: 1395-1397

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Abstract

Interaction of o-phenylenediamine with 1,4-Bis-(ethoxycarbonyl)-2,5-diamino-1,4-cyclo-hexadiene (1) gave 2, which cyclised to the hexahydrobenzodiazepinone (3). On the other hand, interaction of 1 with o-aminophenol, gave compound 4 which on treatment with polyphosphoric acid gave the tetrahydrobis-benzooxazepinone (11). Treatment of 1 with phenylisothiocyanate and formamide afforded the dithiopyrimidoquinazolinone (8) and the tetrahydropyrimidoquinazolinone (9), while the interaction of 1 with benzenesulphonyl-chloride gave dibenzenesulphonamido-cyclohexadiene dicarboxylate (10). The structure of these compounds was established by chemical and spectroscopic methods.

Open Access June 2, 2014

Synthese und Reaktionen von Enaminosulfoniumsalzen / Syntheses and Reactions of Enaminosulfonium Salts

Heinz Braun, Anton Amann, Robert Barnert, Joachim Firl

Page range: 1398-1405

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Abstract

A general method for preparing (E)-alkylamino and dialkylamino vinylsulfonium salts is reported. The hydrolysis and some alkylation and acylation reactions have been examined. The 2,2-dihydroxyethyl sulfonium salt (9 a) is produced by acid hydrolysis of 4 a. In the reaction of 4h with trimethyloxonium salt and acyl halides the N-alkylated and N-acylated products 4 a and 11 are formed respectively. (E)-N,N-diacylated compounds (12) are obtained from 41 and 51 by the reaction with excess acyl halides. On treatment with base, 11a forms mixtures of the (E)- and (Z)-sulfonium imido ylides 14 and 15.

Open Access June 2, 2014

Dynamisches Verhalten, Konformation und Bindungsverhältnisse von Enaminosulfoniumsalzen / Dynamic Behaviour, Conformation and Bonding of Enaminosulfonium Salts

Joachim Firl, Heinz Braun, Anton Amann, Robert Barnert

Page range: 1406-1414

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Abstract

The rotational barriers about the C-N single bond of the enaminosulfonium salts 1-6 are measured. Their magnitudes are related to the π-donor strength of the NR 2 group. For the unsymmetrically substituted compounds 7-12 the rotational equilibria are determined. In the case of the monoalkyl compounds 7-10 the more crowded s-cis-rotamers turn out to be the more stable conformations. Furthermore, the 13 C chemical shifts of the sulfonium salts 1-16 are reported. The shift differences δ(s-cis-s-trans) for the α-carbons of the N-alkyl groups seem to depend on the dihedral angle between the vinyl group and the C-H (α-c) bonds. Moreover, the spectra reveal that enaminosulfonium salts posses a high degree of ylide character.

Open Access June 2, 2014

Salts of Ferricinium Cation and its Homologues: NMR Investigation, II EPR and NMR Spectra of sym-Polymethyl Substituted Ferricinium Cations

R. B. Materikova, V. N. Babin, S. P. Solodovnikov, I. R. Lyatifov, P. V. Petrovsky, E. I. Fedin

Page range: 1415-1419

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Abstract

The EPR, 1 H and 13 C NMR spectra of methylferricinium hexafluorophosphates, [(Me n Cp) 2 Fe]PF 6 , n = 0-5, have been recorded. HFS constants have been estimated for all the ligand atoms. The general pattern of the spin density distribution is shown to depend on the superposition of the various mechanisms of spin delocalization. For the majority of the cations the determining factors has been found to be represented by spin polarization over the π-skeleton.

Open Access June 2, 2014

Synthese S-substituierter Benzile und einiger gehinderter Biphenyle [1] / Synthesis of S-Substituted Benzils and Some Hindered Biphenyls [1]

Reinhard Lüdersdorf, Jürgen Mai, Klaus Praefcke

Page range: 1420-1425

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Abstract

Three methylthio and/or methylsulfinyl substituted benzils (2, 6 and 7) have been synthesized on photo-or thermochemical routes, respectively. Photodecarboxylation of some new different substituted mesityl benzoates (1 a-e) leads to hindered biphenyls (3 a-e) accompanied sometimes by aldehyde (4a-c) and benzil formation (2) due to compatitive a-cleavage and subsequent stabilization processes of such generated free aroyl radicals. A short summary on constitutional conditions for intramolecular photoredox reactions of ortho functionalized aryl sulfinyl compounds is presented.

Open Access June 2, 2014

Konkurrenzreaktionen bei [3+2]-Cycloadditionen [1] Abfangreaktionen von Nitril-yliden mit 1.1-Diphenylethylen [2] / Competition between [3+2] Cycloaddition and 1,3-Addition Reactions [1] Trapping Reactions of Nitrile Ylides with 1,1-Diphenylethylene [2]

Klaus Burger, Herbert Goth, Wolf-Dieter Roth

Page range: 1426-1430

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Abstract

Trapping reactions of bis(trifluoromethyl) substituted nitrile ylides with 1,1-diphenylethylene are described. Two regioisomeric [3 + 2] cycloadducts, and an open chain product can be isolated. The product ratio was found to be dependent on solvent polarity.

Open Access June 2, 2014

Untersuchungen an quartären Pyridinium-Salzen, XIII [1] Reaktion von Carbonsäureamiden mit Pseudobasen der Pyridinreihe / Investigations of Quaternary Pyridinium Salts, XIII [1] Reaction of Carboxamides with Pseudobases from Pyridine Derivatives

Wolf-H. Gündel

Page range: 1431-1434

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Abstract

Pyridinium salts react in aqueous solution to pseudobases, which give on addition of carboxamides N-(1,4-Dihydro-4-pyridyl)-carboxamides.

Open Access June 2, 2014

Studies on Vitamin B₁₂ and Related Compounds, 51 [1] Direct Syntheses of Alkylcobalamins from Alkanes and Vitamin B_12r under "Oxidizing-Reducing" Conditions

Abdussalam Maihub, Hui Bi Xu, Gerhard N. Schrauzer

Page range: 1435-1438

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Abstract

Syntheses of methylcobalamin from methane, and of n-alkylcobalamins from n-alkanes (C 2 →C 10 ) and vitamin B 12r are described. The compounds are formed under "oxidizing-reducing" conditions: Oxygen radicals (O 2 -, HOO·, and HO·) are generated from the reaction of O 2 with reducing metal ions, notably V +3 (aq) and abstract hydrogen from the alkane substrates. The resulting alkyl radicals are captured by vitamin Bj2r with high efficiency to yield alkylcobalamins. The reactions take place at room temperature in mildly alkaline or acidic solutions. In addition to n-alkylcobalamins, the preparation of neopentylcobalamin from neopentane, of isobutylcobalamin from isobutane, and of several cycloalkylcobalamins from cycloalkanes, is also reported. Methyl radicals generated in D 2 O from CH 4 under "oxidizing-reducing" conditions are reduced to yield CH 3 D.

Open Access June 2, 2014

The Chemical Evolution of a Nitrogenase Model, XIX Simulation of the Enzymatic Reduction of Cyclopropene

Gerhard N. Schrauzer, Laura A. Hughes, Miles R. Palmer, Norman Strampach, Jay W. Grate

Page range: 1439-1443

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Abstract

The nonenzymatic reduction of cyclopropene in molybdothiol-and related model systems of nitrogenase yields cyclopropane and propylene in a pH-dependent fashion: In alkaline media, cyclopropane is formed exclusively. In acidic solutions, cyclopropane and propylene are produced. Cyclopropene is thus identified as a pH sensitive chemical probe of nitrogenase. Since substantial amounts of propylene are formed in the enzymatic reduction of cyclopropene, it follows that the active site in functioning nitrogenase is in a locally acidic environment. The protons required to sustain the acidic pH are presumably generated by ATP hydrolysis; addition of substrate amounts of ATP to nonenzymatic cyclopropene reducing systems also stimulates propylene-and cyclopropane production. The stereochemical course of cyclopropene reduction to cyclopropane is exclusively cis, both under enzymatic and nonenzymatic conditions. The formation of propylene from cyclopropene is not stereoselective and mechanistically consistent with acid catalyzed ring opening prior to reduction.

Open Access June 2, 2014

Solubilization and Photoreaction of Thiazine Dyes in Reversed Micelles

Norio Miyoshi, Giiti Tomita

Page range: 1444-1448

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Abstract

Thiazine dyes were solubilized very slowly in dodecylammonium propionate reversed micellar cyclohexanic solutions containing 0.5 M H 2 O. Light accelerated highly the solubilization of the dyes. The dye monomer band blue-or red-shifted by the solubilization dependent on the dye species. Thiazine dyes solubilized in the reversed micelles containing 0.1 M H 2 O exhibited a new absorption band at about 500 nm. The photoreduction of thiazine dyes by allylthiourea was enhanced drastically by solubilizing the dyes in the reversed micellar solutions containing 0.5 M H 2 O, and the singlet oxygen production was also effectively photosensitized by the solubilized thiazine dyes. The relative quantum yields for the photoreduction of the dyes by allylthiourea and the furan oxidation by singlet oxygen produced by the photosensitization of the dyes were obtained in the reversed micellar solutions. Results obtained were discussed in connection with the solubilization.

Open Access June 2, 2014

1,2-Dimethoxy-4-isopropoxy-5-vinylbenzene, an Insect anti-Juvenile Hormone Lacking the Chromene Ring

G. Matolcsy, Y. M. Darwish, I. Bélai, L. Varjas, A. I. Farag

Page range: 1449-1450

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Abstract

The chromene derivative precocene II (1) induces precocious metamorphosis and sterility on some insects, while β-asarone (2), which does not contain a chromene ring, reveales sterilant action without causing developmental disturbances. Based on the common structural features of these two substances, some of their analogues containing their structural elements have been prepared and tested on the cotton bug, Dysdercus cingulatus to investigate structural requirements of activity. The title compound 3 lacking the chromene ring induced symptoms similar to those of precocene II, indicating that the chromene ring structure is not necessary for this action.

Open Access June 2, 2014

Synthese von cis-und trans-4-Cyanocyclohexanol / Synthesis of cis-and trans-4-Cyanocyclohexanol

Klaus Praefcke, Dietmar Schmidt

Page range: 1451-1454

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Abstract

The synthesis of cis-and trans-4-cyanocyclohexanol 2 a and 2 b is described for the first time. Their stereochemistry has been determined by 1 H NMR spectroscopy.

Open Access June 2, 2014

A Comparison of the Effects of Steric Crowding at Phosphorus on the Steric Course of Wittig Reactions of Stabilised and Semistabilised Ylides

David W. Allen

Page range: 1455-1458

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Abstract

The cis-trans ratio of the alkenes formed in Wittig reactions of semistabilised ylides (derived from benzyltriarylphosphonium salts in ethanolic sodium ethoxide) with benz-aldehyde, acetaldehyde or trimethylacetaldehyde increases as steric crowding at phos-phorus increases. In contrast, the cis-trans ratio of the unsaturated esters formed in the related reactions of the stabilised ethoxycarbonylmethylene ylides decreases as steric crowding at phosphorus increases. The relevance of these results to recent proposals for the mechanism of the Wittig reaction is considered.

Open Access June 2, 2014

Untersuchungen an natürlichen γ und δ-Laktonen, X [1] Synthese von Umuravumbolid und Epiumuravumbolid / Investigations on Naturally Occuring γ-and δ-Lactones, X [1] Synthesis of Umuravumbolide and Epiumuravumbolide

Hans Achenbach, Joachim Witzke

Page range: 1459-1464

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Abstract

6-(3-Acetyloxy-1-heptenyl)-5,6-dihydro-2H-pyran-2-one (= umuravumbolide), the new α-pyrone recently isolated from leaves of the central African Iboza riparia, and its diastereomer, epiumuravumbolide, were synthesised.

Open Access June 2, 2014

Alkaloide in Tabernaemontana-Arten, XIII [1] Ibophyllidin und Ibophyllidin-N_b-oxid, Alkaloide in Tabernaemontana flavicans / Alkaloids in Tabernaemontana-Species, XIII [1] Ibophyllidine and Ibophyllidine-N_b-oxide, Alkaloids in Tabernaemontana flavicans

Hans Achenbach, Bernd Raffelsberger

Page range: 1465-1469

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Abstract

From the basic extract of Tabernaemontana flavicans we isolated the alkaloids 1 and 2 and deduced their structures. Both compounds belong to the relatively rare group of 21-norpandolane type alkaloids.

Open Access June 2, 2014

Struktur-Wirkungsbeziehungen polyfunktioneller Diterpene des Tigliantyps, IV [1-3]. Derivate des Tiglians mit fehlendem oder geöffnetem Cyclopropanring und ihre irritierende und tumorpromovierende Wirkung / Structure-Activity Relationships of Polyfunctional Diterpenes of the Tigliane Type, IV [1-3]. Derivatives of Tigliane without or with Opened Cyclopropane Ring and their Irritant and Promoting Activity

Bernd Sorg, Michael Gschwendt, Heinz Walter Thielmann, Erich Hecker

Page range: 1470-1475

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Abstract

The synthesis of the esters 6d-8d, 9 c and 10 c is described. These compounds are closely structurally related to the irritant and tumorpromoting 12-O-tetradecanoylphorbol-13-acetate (TPA, 2 a) and to phorbol-12,13-didecanoate (PDD, 2 c) except that they possess no cyclopropane ring. Biological tests show that opening or complete removal of the cyclopropane ring leads to nearly total loss of irritant or tumorpromoting (tested in the case of 9 c and 10 c) activity.

Open Access June 2, 2014

Solid Phase Synthesis of Thymopoietin-(32-36) Using Adpoc Amino Acids and its Biological Activity ⁺

Georg Rampold, Elsa Lundanes, Karl Folkers, Wolfgang Voelter, Hubert Kalbacher, Emile Bliznakov

Page range: 1476-1478

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Abstract

An exemplary peptide has been synthesized for the first time by an automated solid-phase instrumentation which utilized the new Adpoc (1 -(1-adamantyl) -1 -methylethoxycarbonyl-) group for protection of the a-amino groups of the amino acids. The pentapeptide, thymo-poietin-(32-36) was synthesized, and shown to be pure by criteria including HPLC. Using a Cytoxan (cyclophosphamide) model system for suppression of a primary, hemolytic, humoral, antibody level, thymopoietin-(32-36) showed low activity, and reversed the suppressing effect of Cytoxan. This biological activity apparently is the result of cummulative effect.

Open Access June 2, 2014

NOTIZEN. The Conformations of Oxacyclooctanes

Ulrich Burkert

Page range: 1479-1481

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Abstract

The geometries and energies of the conformers of oxocane, the isomeric di-and trioxocanes, and of 1,3,5,7-tetroxocane were calculated by molecular mechanics. A boat-chair conformation was preferred by all molecules. From the preference of oxygen in the boat-chair conformations of oxocane (position 3 over 1 over 4) the preferred boat-chair form of all other oxocanes can be derived. The results are compared to experi-mental data, which in part can be reinterpreted. Additional CNDO/2 and MINDO/3 calculations were performed for 1,3,5,7-tetroxocane.

Open Access June 2, 2014

Darstellung und Struktur von NaAu₃Si und NaAu₃Ge / Preparation and Crystal Structure of NaAu₃Si and NaAu₃Ge

Page range: 1482-1483

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Abstract

In the course of our investigations of the ternary systems Na-Au-Si(Ge) we obtained the new compounds NaAu 3 Si and NaAu 3 Ge. Their crystal structure has been determined from single crystal X-ray diffraction data. They crystallize in the cubic space group Pa 3 with unit cell parameters a = 891,6 pm and a = 902,1 pm, resp., and Z = 8.

Open Access June 2, 2014

Neuartige Cycloaddition eines Benzocyclobutadiens mit Dienophilen A New Cycloaddition of a Benzocyclobutadiene with Dienophiles / A New Cycloaddition of a Benzocyclobutadiene with Dienophiles

Henner Straub, Bernd Miller

Page range: 1484-1485

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Abstract

trans -1,2 -Dicy ano -and tetracyanoethylene add to 1,2-di-tert-butyl-3,4,5,6-tetramethyl-benzocyclobutadiene (1b) neither angular nor linear but give the bridged compounds across the six-membered ring 2 b and 3 b respectively.

Open Access June 2, 2014

1-und 2-Methylallylkationen aus isomeren Vinylbromidradikalkationen / 1-and 2-Methylallyl Cations from Cation Radicals of Isomeric Vinyl Bromides

Helmut Schwarz, Chrysostomos Wesdemiotis

Page range: 1486-1487

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Abstract

It is demonstrated by collisional activation mass spectrometry that dissociative ionization of E-and Z-1-bromobutene-1 (3, 4), 2-bromo-butene-1 (5) and 2-bromobutene-2 (6) yields exclusively 1-methylallyl cation (a). Unimolecular Br -loss from the molecular ion of 1-bromo-2-methylpropene (7) gives rise to the specific formation of the isomeric 2-methylallyl cation (b). Kinetic energy release measurements sup-port the interpretation that Br' loss from the cation radicals 3-7 is preceded (or accompanied) by an exothermic isomerization of the incipient C 4 H 7 + ions.

Open Access June 2, 2014

Photoinduzierte Wasserstoffübertragungs - reaktionen der chlorierten Octahydro-1.4-endo, endo-5.8-dimethanonaphthaline / Photoinduced Hydrogentransferreactions of Chlorinated Octahydro-1,4-endo, endo-5,8-dimethanonaphthaline

H. Parlar, F. Korte

Page range: 1488-1490

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Abstract

Photokinetic experiments show that a series of chlorinated octahydro-1,4-endo, endo-5,8-dimethanonaphthaline (1-4) react intramolecular and via tripletstate to their photoisomers (1 a-4a). The formation of the compounds 1 a-4a is dependent on oxygen and nature of sensitizers.

Open Access June 2, 2014

Optisch aktive Übergangsmetall-Komplexe, LXX [1]. Darstellung der optisch aktiven Diastereomeren C₅H₅Fe(CO)- (CH₂OCH₃)P(C₆H₅)₂N(CH₃)R* mit chiralen Fe-Atomen / Optically Active Transition Metal Complexes, LXX [1]. Preparation of the Optically Active Diastereoisomers C₅H₅Fe(O)- (CH₂OCH₃)P(C₆H₅)₂N(CH₃)R* with Chiral Fe Atoms

Henri Brunner, Jean-Claude Leblanc

Page range: 1491-1493

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Abstract

The two diastereoisomers C 5 H 5 Fe(CO)(CH 2 OCH 3 )P(C 6 H 5 ) 2 N(CH 3 )R* (Ba, b), with R* = (S)·CH(CH 3 )(C 6 H 5 ), differing only in the Fe configuration, have been obtained by photochemical reaction of C 5 H 5 Fe(CO) 2 CH 2 OCH 3 with (S)-(+)-P(C 6 H 5 ) 2 N(CH 3 )R*. The optically pure isomer 3 a can be isolated by chromatography at low temperature; its chiroptical properties are discussed.

Open Access June 2, 2014

Mesylhydroxylamine, IV [1] Silylierte N-Mesylhydroxylamine / Mesylhydroxylamines, IV [1] Silylated N-Mesylhydroxylamines

Gerd Pohlmann, Klaus Brink, Claus Bliefert

Page range: 1494-1495

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Abstract

The preparation and some properties of the two silylated N-Mesylhydroxylamines, CH 3 SO 2 N(H)OSi(CH 3 ) 3 and CH 3 SO 2 N[Si(CH 3 ) 3 ]OSi(CH 3 ) 3 , are reported.

Open Access June 2, 2014

Polarographic Behaviour of Some Steroidal Olefins

Manfred Wilk, Karlheinz Schmitt

Page range: 1496-1496

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Abstract

Halve-wave-potentials of five steroidal olefins were measured by anodic polarography. They show oxidation-potentials in the range of 0.7-0.9 V. Differences in potentials are correlated to shape of the molecules.

Open Access June 2, 2014

Isolation of a New Natural Quinone, 2-Hydroxy-6-methoxy-3,5-dimethyl- 1,4-benzoquinone, from the Potato Culture Solution of Phoma wasabiae Yokogi

Osamu Soga, Hidetoshi Iwamoto

Page range: 1497-1497

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Abstract

2-Hydroxy-6-methoxy-3,5-dimethyl -1,4- benzoquinone was found in the blackish potato culture solution of Phoma wasabiae.

About this journal

Objective
Zeitschrift fuer Naturforschung B (ZNB) publishes novel research in all areas of inorganic chemistry, organic chemistry, and analytical chemistry. In particular, the journal focuses on solid state chemistry, coordination chemistry, main group element chemistry, synthetic organic chemistry, natural product chemistry and, to a lesser extent, on analytical chemistry. For more than 65 years Zeitschrift fuer Naturforschung B has been open to contributions from all fields of experimental and theoretical chemistry. Zeitschrift fuer Naturforschung B publishes 12 issues per volume/year. Sometimes double issues occur.

Topics

Solid state chemistry
Coordination chemistry
Main group element chemistry
Organic chemistry
Natural product chemistry

Article formats
Original (full) papers, research notes and preliminary communications, reports on specific research topics of current interest (reviews)

> Information on submission process

Volume 35 Issue 11

Issue of Zeitschrift für Naturforschung B

Neue phosphororganische Liganden: 2-Pyridyl-phosphane, -phosphanmethylene und -phosphanborane / New Organophosphorus Ligands: 2-Pyridyl-phosphanes, -phosphanemethylenes, and -phosphaneboranes

Abstract

Über die Reaktion von Trifluorphosphin (PF3), Difluormethylphosphit (F2POCH3) und Trimethylphosphit [P(OCH3)3] mit Aquacobalamin in Methanol / On the Reaction of Trifluorophosphine (PF3), Difluoromethylphosphite (F2POCH3) and Trimethylphosphite [P(OCH3)3] with Aquacobalamin in Methanol

Abstract

Zur Kenntnis farbiger ternärer und quaternärer Zintl-Phasen / Coloured Ternary and Quaternary Zintl-Phases

Abstract

Struktur und Eigenschaften des Kaliumhydrogendiarsenit-Hemihydrats, KHAs2O4 · 1/2 H2O / Structure and Properties of the Potassiumhydrogendiarsenite-hemihydrate, KHAs2O4 · 1/2 H2O

Abstract

Abstract

Darstellung und Charakterisierung der Tetrabutylammoniumsalze der Tetrahalogenooxotechnetate(V), [TcOCl4]- und [TcOBr4]- / Preparation and Characterization of the Tetrabutylammonium Salts of the Tetrahalooxotechnetates(V), [TcOCl4]- and [TcOBr4]-

Abstract

Ringkontraktion am Cyclotrisilazan -System - Synthese und Molekülstrukturen zweifach silylverknüpfter Cyclodisilazane / Ring Contraction in the Cyclotrisilazane System - Synthesis and Molecular Structures of Silyl-Bridged Cyclodisilazanes

Abstract

Über zwei Modifikationen von "Tl2Cl3"-valenzgemischten Thallium(I)-hexahalogenothallaten(III) Tl3 [TlCl6] / On Two Modifications of "Tl2Cl3"-Mixed Valence Thallium(I)-hexahalogenothallates(III)

Abstract

Darstellung, Eigenschaften und Kristallstruktur von 6-Methyl-4-Methylen-2-Phenyl-4 H-1.3.2-dioxaphosphorin / Preparation, Properties and Crystal Data of 6-Methyl-4-methylen-2-phenyl-4 H-1,3,2-dioxaphosphorin

Abstract

Darstellung von (Trimethylsilylmetliyl)gallium-Verbindungen / Preparation of (Trimethylsilylmethyl)gallium Compounds

Abstract

X-ray Structural Analyses of Two Allotropes of Cycloheptasulfur ( γ and δ-S7 ) [1]

Abstract

Abstract

O.O-Diphenyl-N-chloramidophosphat / 0,0-Diphenyl-N-chlorophosphoramidate

Abstract

Arsenverbrückte zweikernige Mn(CO)4Br-Komplexe / Arsenic Bridged Dinuclear Mn(CO)4Br Complexes

Abstract

Synthesis of Some Diazepinones, Oxazepinones, Pyrimidoquinazolinones and Related Compounds from 1,4-Bis(ethoxycarbonyl)-2,5-diamino-1,4-cyclohexadiene

Abstract

Synthese und Reaktionen von Enaminosulfoniumsalzen / Syntheses and Reactions of Enaminosulfonium Salts

Abstract

Dynamisches Verhalten, Konformation und Bindungsverhältnisse von Enaminosulfoniumsalzen / Dynamic Behaviour, Conformation and Bonding of Enaminosulfonium Salts

Abstract

Salts of Ferricinium Cation and its Homologues: NMR Investigation, II EPR and NMR Spectra of sym-Polymethyl Substituted Ferricinium Cations

Abstract

Synthese S-substituierter Benzile und einiger gehinderter Biphenyle [1] / Synthesis of S-Substituted Benzils and Some Hindered Biphenyls [1]

Abstract

Konkurrenzreaktionen bei [3+2]-Cycloadditionen [1] Abfangreaktionen von Nitril-yliden mit 1.1-Diphenylethylen [2] / Competition between [3+2] Cycloaddition and 1,3-Addition Reactions [1] Trapping Reactions of Nitrile Ylides with 1,1-Diphenylethylene [2]

Abstract

Untersuchungen an quartären Pyridinium-Salzen, XIII [1] Reaktion von Carbonsäureamiden mit Pseudobasen der Pyridinreihe / Investigations of Quaternary Pyridinium Salts, XIII [1] Reaction of Carboxamides with Pseudobases from Pyridine Derivatives

Abstract

Studies on Vitamin B12 and Related Compounds, 51 [1] Direct Syntheses of Alkylcobalamins from Alkanes and Vitamin B12r under "Oxidizing-Reducing" Conditions

Abstract

The Chemical Evolution of a Nitrogenase Model, XIX Simulation of the Enzymatic Reduction of Cyclopropene

Abstract

Solubilization and Photoreaction of Thiazine Dyes in Reversed Micelles

Abstract

1,2-Dimethoxy-4-isopropoxy-5-vinylbenzene, an Insect anti-Juvenile Hormone Lacking the Chromene Ring

Abstract

Synthese von cis-und trans-4-Cyanocyclohexanol / Synthesis of cis-and trans-4-Cyanocyclohexanol

Abstract

A Comparison of the Effects of Steric Crowding at Phosphorus on the Steric Course of Wittig Reactions of Stabilised and Semistabilised Ylides

Abstract

Untersuchungen an natürlichen γ und δ-Laktonen, X [1] Synthese von Umuravumbolid und Epiumuravumbolid / Investigations on Naturally Occuring γ-and δ-Lactones, X [1] Synthesis of Umuravumbolide and Epiumuravumbolide

Abstract

Alkaloide in Tabernaemontana-Arten, XIII [1] Ibophyllidin und Ibophyllidin-Nb-oxid, Alkaloide in Tabernaemontana flavicans / Alkaloids in Tabernaemontana-Species, XIII [1] Ibophyllidine and Ibophyllidine-Nb-oxide, Alkaloids in Tabernaemontana flavicans

Abstract

Abstract

Solid Phase Synthesis of Thymopoietin-(32-36) Using Adpoc Amino Acids and its Biological Activity +

Abstract

NOTIZEN. The Conformations of Oxacyclooctanes

Abstract

Darstellung und Struktur von NaAu3Si und NaAu3Ge / Preparation and Crystal Structure of NaAu3Si and NaAu3Ge

Abstract

Neuartige Cycloaddition eines Benzocyclobutadiens mit Dienophilen A New Cycloaddition of a Benzocyclobutadiene with Dienophiles / A New Cycloaddition of a Benzocyclobutadiene with Dienophiles

Abstract

1-und 2-Methylallylkationen aus isomeren Vinylbromidradikalkationen / 1-and 2-Methylallyl Cations from Cation Radicals of Isomeric Vinyl Bromides

Abstract

Photoinduzierte Wasserstoffübertragungs - reaktionen der chlorierten Octahydro-1.4-endo, endo-5.8-dimethanonaphthaline / Photoinduced Hydrogentransferreactions of Chlorinated Octahydro-1,4-endo, endo-5,8-dimethanonaphthaline

Abstract

Abstract

Mesylhydroxylamine, IV [1] Silylierte N-Mesylhydroxylamine / Mesylhydroxylamines, IV [1] Silylated N-Mesylhydroxylamines

Abstract

Polarographic Behaviour of Some Steroidal Olefins

Abstract

Isolation of a New Natural Quinone, 2-Hydroxy-6-methoxy-3,5-dimethyl- 1,4-benzoquinone, from the Potato Culture Solution of Phoma wasabiae Yokogi

Abstract

Struktur und Eigenschaften des Kaliumhydrogendiarsenit-Hemihydrats, KHAs₂O₄ · 1/2 H₂O / Structure and Properties of the Potassiumhydrogendiarsenite-hemihydrate, KHAs₂O₄ · 1/2 H₂O

Darstellung und Charakterisierung der Tetrabutylammoniumsalze der Tetrahalogenooxotechnetate(V), [TcOCl₄]^- und [TcOBr₄]^- / Preparation and Characterization of the Tetrabutylammonium Salts of the Tetrahalooxotechnetates(V), [TcOCl₄]^- and [TcOBr₄]^-

Über zwei Modifikationen von "Tl₂Cl₃"-valenzgemischten Thallium(I)-hexahalogenothallaten(III) Tl₃ [TlCl₆] / On Two Modifications of "Tl₂Cl₃"-Mixed Valence Thallium(I)-hexahalogenothallates(III)

X-ray Structural Analyses of Two Allotropes of Cycloheptasulfur ( γ and δ-S₇ ) [1]

Arsenverbrückte zweikernige Mn(CO)₄Br-Komplexe / Arsenic Bridged Dinuclear Mn(CO)₄Br Complexes

Studies on Vitamin B₁₂ and Related Compounds, 51 [1] Direct Syntheses of Alkylcobalamins from Alkanes and Vitamin B_12r under "Oxidizing-Reducing" Conditions

Alkaloide in Tabernaemontana-Arten, XIII [1] Ibophyllidin und Ibophyllidin-N_b-oxid, Alkaloide in Tabernaemontana flavicans / Alkaloids in Tabernaemontana-Species, XIII [1] Ibophyllidine and Ibophyllidine-N_b-oxide, Alkaloids in Tabernaemontana flavicans

Solid Phase Synthesis of Thymopoietin-(32-36) Using Adpoc Amino Acids and its Biological Activity ⁺

Darstellung und Struktur von NaAu₃Si und NaAu₃Ge / Preparation and Crystal Structure of NaAu₃Si and NaAu₃Ge