Synthesis of 6-phenyl and 6-styrylthiazolo[3,2-b] [1,2,4]triazoles

Thiazole rings have been often encountered in the structure of antibiotic or antitumor drugs. An easy synthesis of them has revealed itself necessary in order to elucidate the mechanism of action of these naturally occurring substances. A method of preparation of conjugated b-ethylenic thiazole[3,2-b] [1,2,4]triazoles by heating a 3-thio substituted [1,2,4]triazole in the presence of polyphosphoric acid is reported here, giving the expected product in a 60% yield.     

Synthesis of hydroxy-6H-benzofuro[3,2-c] [1]benzopyran-6-ones

The Micheal addition of ethyl 2-methoxy-, 2,4-dimethoxy- and 2,5-dimethoxybenzoylacetates with benzoquinone leads to ethyl 2-(rnethoxy or dimethoxy phenyl)-5-hydroxybenzofuran 3-carboxylates. Treatment of the henzofuran derivatives with anhydrous pyridine hydrochloride at 190–195° leads to hydroxy-6H-henzofuro[3,2-c] [1]benzopyran-6-ones.     

K6[Mn2O6] und K6[Fe2 O6] - ein Vergleich

K₆[Mn₂O₆] and K₆[Fe₂O₆] - a Comparison K₆[Mn₂O₆] has been prepared (dark-red single crystals). The structure (a = 8.88₆, b = 6.76₀, c = 11.39₄ Å, γ = 132.1°, space group P2₁, Z = 2, 1151 symmetry independent reflections hk0–hk9, R = 0.051) shows Al₂Cl₆-like anions [Mn₂O₆]^6?. By unit-cell transformation to the monoclinic setting P2₁/a (a = 6.76₀, b = 11.39₄, c = 6.63₈ Å, β = 96,9°) the structural similarity to K₆[Fe₂O₆] becomes evident. The Madelung Part of Lattice Energy, MAPLE, is calculated.     

Spectrophotometric study of the supramolecular complexes of [60]- and [70]Fullerenes with biscalix[6]arene and crown[4]calix[6]arene

[60]- and [70]Fullerenes have been shown to form 1:1 supramolecular complexes with bis[2-(5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41-pentahydroxycalix[6]arenyl-oxy ethyl ether) (1) and 5,11,17,23,29,35-hexa-tert-butyl-37,38,40,41-tetra hydroxyl-39,42-(crown-4)calix[6]arene (2) in CHCl3 medium by electronic absorption spectroscopy. Formation constants (K) of the complexes of [60]- and [70]fullerenes with 1 and 2 have been determined at room temperature from which free energy of formation values of the complexes have been estimated. The very high formation constant value of [60]fullerene/1 complex (5900 dm3 mol-1) in indicative of formation of inclusion complex. Moreover, PM3 calculations reveal that intermolecular interaction between [60]fullerene and 1 proceeds through quite deep energy molecular orbital.     

Helic[6]arene-Based Chiral Pseudo[1]rotaxanes and [1]Rotaxanes

Chiral pseudo[1]rotaxanes and [1]rotaxanes constructed from macrocyclic arenes still remain a big challenge mainly owing to the lack of such chiral macrocycles. In this work, a new system of chiral pseudo[1]rotaxanes formed by self-inclusion of helic[6]arene containing amide linked with the terminal tertiary amines was first discovered. Based on an atom-economic stopping strategy, a pair of chiral [1]rotaxanes were conveniently obtained in almost quantitative yields by blocking the pseudo[1]rotaxanes with monobenzyl bromide of tetraphenylethene. The structures of pseudo[1]rotaxanes and [1]rotaxanes were characterized by 2D NMR spectra in solution, combined with DFT calculations. The photophysical properties further revealed the efficient chirality transfer of helic[6]arene to the tetraphenylethene moiety, compared to their unthreaded chiral isomers. The discovery of the chiral pseudo[1]rotaxanes allows for a wide and available synthesis of chiral [1]rotaxanes, and also opening a new avenue to the design of chiral supramolecular materials.     

Convenient Synthesis of 6H-[1,2,4,5]Tetrazino[3,2-b]quinazolin-6-ones

Summary.  The reaction of 3-amino-2-thioxo-4(1H)-quinazolinone or its 2-methylthio derivative with hydrazonoyl halides in the presence of ethanol and triethylamine affords 6H-[1,2,4,5]tetrazino[3, 2-b]quinazolin-6-ones. Received January 2, 2001. Accepted (revised) April 11, 2001     

Darstellung und Kristallstruktur von K6[Al2O6] und Rb6[Al2O6]

Preparation of Crystal Structure of K₆[Al₂O₆] and Rb₆[Al₂O₆] Colourless single crystals of K₆[Al₂O₆] have been prepared from intimate mixtures of KAlO₂ and K₂O (550°C, 90 d). The structure determination from four-circle diffractometer data (MoKα , 742 I_o(hkl), R = 2.2%, R_w = 2.1%) confirms the space group C2/m with Z = 2; a = 698.25 pm, b = 1 103.54 pm, c = 646.49 pm, β = 102.49°. Colourless single crystals of hitherto unknown Rb₆[Al₂O₆] have been prepared from intimate mixtures of RbAlO₂ and Rb₂O (520°C, 120 d). The structure determination from four-circle diffractometer data (MoKα , 1 240 I_o(hkl)) results in the residual values R = 7.2%, R_w = 4.9%; space group C2/m; a = 725.92 pm, b = 1 143.33 pm, c = 678.06 pm, β = 104.05°; Z = 2. K₆[Al₂O₆] and Rb₆[Al₂O₆] are isostructural with K₆[Fe₂O₆]. A characteristic structure unit is the anion [Al₂O₆]^6? consisting of two edge-sharing [AlO₄] tetrahedra. Effective Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR), the Madelung Part of Lattice Energy (MAPLE) and the Charge Distribution (CHARDI) are calculated and discussed.     

Bridged Calix[6]arenes

Bridging including capping of calix[6]arene is not only an importantroute to synthesize new host molecules, but also an efficient route to reduce the mobility of conformationof calix[6]arene. This article reviews the syntheses, conformations and complexation behavior of this kindof host molecules.     

Die KristallStrukturen von K6[Ge2Te6] und K6[Sn2Te6] und ihre kristall-chemische Beziehung zum K6[Si2Te6]-Typ

Crystal Structures of K₆[Ge₂Te₆] and K₆[Sn₂Te₆] and their Relations to the K₆[Si₂Te₆] Type K₆[Ge₂Te₆] and K₆[Sn₂Te₆], the first members of the families of telluro-digermanates and telluro-distannates have been prepared and their structures determined. The space group is C 2/c with cell constants a = 16.010(8), b = 13.619(8), c = 9.713(5) Å, β = 95.19(5)° and Z = 4 for the Ge compound. The Sn compound has space group P 2₁/c, a = 9.590(5), b = 13.654(8), c = 9.606(5) Å, β = 116.84(5) and Z = 2. The structures were established by direct methods, using four-circle diffractometer data. The final R value for 828 (1677) independent reflexions is 0.068 (0.047) for the Ge (Sn) compound. Both structures have discrete X₂Te₆ groups (X = Ge, Sn) in staggered conformation connected by K atoms in distorted octahedral or trigonal prismatic environments and bear direct subgroup relationships to that of K₆[Si₂Te₆]. The average X? Te distance is 2.579 (2.724) Å and the X? X distance 2.492 (2.814) Å.     

Neues über K2[MnF6], Rb2[MnF6] und Cs2[MnF6]

News on K₂[MnF₆], Rb₂[MnF₆], and Cs₂[MnF₆] Cs₂[MnF₆] (a = 8.97₂ Å) and Rb₂[MnF₆] (a = 8.53₁ Å) as well as this with K₂[MnF₆] (a = 8.22₁ Å and hexagonal a = 5.72₂, c = 9.33₁ Å) form mixed crystals of the K₂PtCl₆ type of structure. Calculations of the Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, lead contrary to former assumptions to distances Mn? F of about 1.86 Å (CN 6).     

Binding behaviors of para-dicyclohexanocucurbit[6]uril and meta-tricyclohexanocucurbit[6]uril with dialkyl viologens

The binding behaviours of para-dicyclohexanocucurbit[6]uril (Cy₂Q[6]) and meta-tricyclohexanocucurbit[6]uril (Cy₃Q[6]) with a series of dialkyl viologens (MV²⁺, EV²⁺, PV²⁺, BV²⁺, FV²⁺ and HV²⁺) have been investigated by various methods. In the aqueous solution, ¹H NMR spectra suggest that the alkyl chains are more favourably encapsulated into the hydrophobic cavities of both hosts than the aromatic rings. Cyclic voltammograms (CV) curves show that the Cy₂Q[6] or Cy₃Q[6] bind the charged viologens more strongly than the reduced viologens. Isothermal titration calorimetry (ITC) data reveal that the binding processes of both hosts with viologens are enthalpic driven. In the solid state, the PV²⁺, BV²⁺ guests and two Cy₃Q[6] hosts generated dumbbell-shaped structures, with two Cy₃Q[6] hosts residing over two terminal alkyl chains of the guests.     

Novel polycyclic heterocycles. XI. Synthesis of 11,12-dihydropyrido[2,1-b] [1,3]benzodiazepines, 6H-pyrido[1,2-c] [1,3,5]benzoxadiazepines,and 6H-Pyrido[1,2-c] [1,3,5]benzothiadiazepines

An unusually facile dehydrobromination, involving the ortho-bromine atom and the = NH proton of a 2-imino-1-(phenethyl)-, 2-imino-1-(phenoxymethyl)-, or 2-imino-1-(phenylthiomethyl)-pyridine ( 2a-e ) has led to the synthesis of three novel bridgehead nitrogen tricyclic systems: 11,12-dihydropyrido[2,1-b] [1,3]benzodiazepines ( 3a,b ), 6H-pyrido[1,2-c] [1,3,5]benzoxadiazepines ( 3c,d ) and 6H-pyrido[1,2-c][1,3,5]benzothiadiazepines ( 3e ). As anticipated, these cyclizations required a base, e.g., potassium carbonate, and a catalyst, e.g., copper bronze. What was unusual, was that these reactions occurred in methanol or n-propanol, under reflux, either under anhydrous conditions, or in the presence of large amounts of water. The pmr spectra of these compounds are discussed.     

3-Methyl[1,3,4]thiadiazino[2,3-b]quinazolin-6-ones

4H,6H-[1,3,4]Thiadiazino[2,3-b]quinazolin-6-one with a methyl group in position 3 (6a) has been synthesised by the condensation of 3-amino-2-mercapto-3H-quinazolin-4-one (1) with allyl bromide (2) followed by treatment with bromine and subsequent dehydrohalogenation of the brominated product (4) with ethanolic sodium hydroxide. Its isomeric 3-methyl-2H,6H-[1,3,4]thiadiazino[2,3-b]quinazolin-6-one (6b) has also been obtained by condensation of1 and bromoacetone (7) followed by cyclisation of the intermediates (8 or9) with hydrobromic acid or with concentrated sulphuric acid. The structures have been established on the basis of IR and PMR data.

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3-Methyl[1,3,4]thiadiazino[2,3-b]chinazolin-6-one

Zusammenfassung Zur Synthese von 4H,6H-[1,3,4]thiadiazino[2,3-b]chinazolin-6-on (6a) wurde die Kondensation von 3-Amino-2-mercapto-3H-chinazolin-4-on (1) mit Allylbromid mit nachfolgender Behandlung mit Brom und Dehydrohalogenierung des bromierten Produktes4 mit ethanolischer Natronlauge herangezogen. Das zu6a isomere 2H,6H-Produkt6b wurde ebenfalls durch Kondensation von1 mit Bromaceton und nachfolgender Cyclisierung der Zwischenprodukte8 bzw.9 mit HBr oder H₂SO₄ erhalten. Die Strukturen wurden mittels IR und NMR abgesichert.