BIRCH-Reduktion von [2.2] Metacyclophan

Metal-ammonia-reduction of [2.2] metacyclophan led to 5, 8, 13, 16-tetrahydro-[2.2] metacyclophan (II). The structure of this new ring system was confirmed by UV.-, NMR.-and mass spectra analyses. The NMR.-spectrum of II in solution shows an AA′ BB′-system for the -CH₂CH₂-groups. This part of the spectrum is temperature dependant. It collapses and coalesces to a broad singlet at approximately 145°C. A chair-like conformation and conformational changes of II are discussed.     

Einkristalle von Ba[NiF6]

Single Crystals of Ba[NiF₆] Transparent, rubin-red single crystals of β-BaNiF₆ were grown unexpectedly by high pressure fluorination [pF₂ > 3500 atm, 450–500°C, 10d; Monel autoclave]. The refinement of the structure [Four circle diffractometer PW 1100, Mo^?Kα; 132 I₀(hkl) 3° < θ < 30°; anisotropic factors of temperature, R = R_W = 3.7%] confirmes the interpretation of powder datas due to them the BaGeF₆ type of structure is present.     

Synthese von [1]Benzothieno[2,3—d]isoxazol-Derivaten

Derivatives of [1]benzothieno[2.3—d]isoxazole, a new heterocyclic ring system, were synthesized by 1.3-dipolar cyclisations: benzo[b]thiophene-1.1-dioxide and its 3-methyl derivative reacted with nitrile oxides and nitrones to the corresponding substituted [1]benzothieno[2.3—d]isoxazolines and-isoxazolidines. Hydrogenolysis of the latter cleaved the isoxazolidine ring, yielding the corresponding 2-(-phenylamino-benzyl)-3-hydroxy-2.3-dihydro-benzo[b]thiophene-1.1-dioxides.

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Mit 1 Abbildung

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Herrn Prof. Dr.E. Hardegger zum 60. Geburtstag gewidmet.     

Reaktion von Formamid mit Kohlenstoffdisulfid 2. Kristallstruktur von Kalium-N-formyldithiocarbamat [1]

On Chalcogenolates. 148. Reaction of Formamide with Carbon Disulfide. 2. Crystal Structure of Potassium N-Formyl Dithiocarbamate K[S₂C? NH? CO? H] crystallizes with Z = 16 in the monoclinic space group Cc with cell dimensions a = 13.187(13) Å, b = 12.928(3) Å, c = 13.962(6) Å, and β = 101.75 (3)°. The crystal structure has been determined from single crystal X-ray data measured at 20°C and refined to a conventional R of 0.034 for 1857 independent reflections (R_w = 0.038). The compound crystallizes by building a super-structure, which is based on an H-bridged 16-membered ring-system, formed by four[S₂C? NH? CO? H]^? anions. Two different binuclear K⁺ coordination polyhedra are formed with two oxygen and two sulfur atoms in common.     

Zur Persistenz von Hexachlorbicyclo-[2.2.1]-hepten-Derivaten

Zusammenfassung Die Persistenz von Hexachlorbicyclo[2.2.1]-hepten-Derivaten wurde unter verschiedenen Bedingungen untersucht, indem die Chlorabspaltung durch Mikrotitration und die Bildung von Reaktionsprodukten gas-chromatographisch verfolgt wurden. Es wurde gefunden, daß eine Dechlorierung des Hexachlorbicyclohepten-Restes, z.B. im Boden, durch pH-Einfluß kaum möglich ist. Die photochemische Dechlorierung, z.B. auf Blattoberflächen oder in der Atmosphäre, kann jedoch als Abbauweg von Bedeutung sein.

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On the persistence of hexachlorobicyclo[2.2.1]-heptene derivatives

The persistence of these compounds has been examined under various conditions by investigating the splitting-off of chlorine by microtitration and the formation of reaction products by gas-chromatography. It has been found that a dechlorination of the hexachlorobicycloheptene radical e.g., in soil, is scarcely possible by the influence of pH. Yet, photochemical dechlorination, e.g. on leaf surfaces and in atmosphere, might be of importance as a way of degradation.

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Die Arbeit wurde aus Mitteln der Deutschen Forschungsgemeinschaft gefördert.     

Synthese von pyridylphenyl-imidazo[2,1-b]thiazolen

The synthesis of the isomeric 6(5)-phenyl-5(6)-pyridyl-2,3-dihydroimidazo[2,1-b]thiazoles are described. Only the synthesis of 5-phenyl-6-(2-pyridyl)-2,3-dihydroimidazo[2,1-b]thiazole failed.     

Synthese von [1]Benzothieno[2,3—c]pyrazol-Derivaten

Derivatives of [1]benzothieno[2.3-c]pyrazole, a new heterocyclic ring system, were synthesized by 1.3-dipolar cycloadditions: benzo[b]thiophene-1.1-dioxide and derivatives thereof reacted with diazomethane and diazoethane to yield substituted [1]benzothieno[2.3-c]pyrazolines. A similar reaction with ethyl diazoacetate gave the corresponding cyclopropa[b][1]benzothiophene-2.2-dioxide derivative.     

Stereochemie von [3.3]- und [5.5]-sigmatropischen umlagerungen

The knowledge of the stereochemical course of Cope and Claisen rearrangements is important both for mechanistic and synthetic reasons. In the first part an analysis of the possible transition state geometries (cf Table 1) for these reactions is given and methods which allow to distinguish between the various geometries are discussed (cf Schemes 1 and 2). In the second part known examples are analyzed. Generally, in Cope and Claisen rearrangements of acyclic systems a chair-like transition state (C) is favoured above a boat-like (B). Steric effects may alter this preference.     

Die Kristallstruktur von CsTcO4 [1]

The Crystal Structure of CsTcO₄ CsTcO₄ crystallizes orthorhombic with a = 5.72₇, b = 5.92₁ and c = 14.34 Å. Z = 4, space group Pnma (Nr. 62, I.T.). The metal positions were refined by single crystal data, the oxygen positions first determined: the CsTcO₄ structure is a slight distortion of the scheelite arrangement (parameters: see text). The MADELUNG Part of Lattice Energy, MAPLE, ?Mean Effective Ionic Radii”?, MEIR, and Effective Coordination Numbers, ECoN, are calculated and discussed.     

Thermisches Verhalten von Cyclopropa[c]chromenen

The Cyclopropa[c]chromenes 14 , trans-and cis- 15 , trans-and cis- 16 and 17 rearrange on heating > 200° in N, N-diethylaniline to give 2-alkyl-2H-chromenes 7, 8, 21, 22. The rate determining step of this rearrangement is the ‘homoelectrocyclic’ ring opening of the cyclopro-pa[c]chromenes to give ω-allyl-quinomethanes of type 4. These intermediates show fast [1,5s] and [1,7a] H-shifts, followed by electrocyclic ring closure. Deuterium labelling experiments are in agreement with this mechanism. The remarkable dependence of the rates of rearrangement with respect to the stereochemistry of the cyclopropa[c]chromenes (cf. table 2) suggests that in the first step only one of the two possible disrotatory modes of ring opening is involved.     

Synthese von 15-Hydroxy[9]metacyclophan

Synthesis of 15-Hydroxy[9]metacyclophane 3-(1-Nitro-2-oxocyclododecyl)propanal ( 1 ) was converted to 15-hydroxy[9]metacyclophane ( 3 ) on two different routes. In the first case the internal aldol reaction product of 1 was treated with K₂CO₃/THF to give 3 in 29 % yield with regard to cyclododecanone. Alternatively, the aldehyde 1 reacted with a primary amine to form e.g. 4 which gave 3 in the presence of CH₃I/K₂CO₃ in 48 % yield.