Syntheses and structures of structurally diverse potassium beta-diketiminates derived from the ligand [(N(SiMe3)C(Ph))2CH

The compounds [K((mu-N(SiMe3)C(Ph))2CH)(thf)2]infinity 1, [K(mu-N(SiMe3)C(Ph)C(H)C(Ph)NH)L]2 [L = (thf)2 2, tmen 3], [K(mu-NSi(Me)2C(Ph)C(H)C(Ph)N)(thf)3]2 4 and [K(N(H)C(Ph))2CH](thf)0.5 5 have been prepared from K[(N(SiMe3)C(Ph))2CH] and the X-ray structures of 1-4 are reported.     

Thermal behaviourof complexes of antipyrine derivatives Part III.

The thermal behaviour of the mixed-ligand complexes of cobalt(II) and copper(I) ions with antipyrine derivatives of 1,2-ethanediamine or piperazine (BAMP and TAMEN), with water and with 2-mercapto-benzothiazole (Hmbt) was investigated. The complexes contain 2-mercaptobenzothiazole (Hmbt, in the case of cobalt(II) ion) or dimercaptobenzothiazine (mbt–mbt, in the case of copper(I) ion) molecules as ligands and perchlorate (ClO₄^–) or thiocyanate (SCN – ) ion as counterion. By heating, water and ligands release the solid phase at lower temperature. At higher temperatures process of different organic reactions of ligands (e.g. polymerization, polycondensation) could be suggested to interpret the relative high final mass values.     

Nucleocyclitols. Synthesis of substituted purinyl-muco-inositol derivatives

Several carbocyclic nucleoside analogs possessing a 6-substituted purine linked to a mesylated muco-inositol were synthesized. The coupling of triethylamine-activated 6-chloropurine with 2,3-anhydro-l,5,6-tri-O-(methanesulfonyl)-epi-inositol gave a 6-chloro purinyl muco-inositol amenable to further synthetic transformations in the heterocyclic moiety by substitution of the chlorine atom by nitrogen nucleophiles such as methylamino, diethylamino, benzylamino, hydrazino, morpholino, hydroxylamino, piperidino, and glycyl groups.     

Chiral induction in self-assembled helicates: CHIRAGEN type ligands with ferrocene bridging units

The aim of this work was the preparation of enantiomerically pure bis(pinene-bipyridine) ligands containing the ferrocenyl moiety. Several such ligands (1-3) were synthesized and completely characterized. These molecules can be diastereoselectively deprotonated at the acidic methylene group of the pinene moiety using a strong and sterically hindered base such as LDA. Subsequent reaction of the formed anion with alkyl halides yield the family of C(2)-symmetric enantiopure compounds (1a-c). Copper(I), silver(I), or zinc(II) complexes with several ligands (C1-C8) were prepared and structurally characterized in the solid state and in solution. Self-assembled helical species are formed in several cases. It became evident that the chiral groups present in the ligand do not completely determined the helical configuration of the assemblages. Diastereoselectivity is thus not complete with this type of ligands, contrary to other, similar ligands studied before.     

Vibrational spectra and infrared dichroism of tetraphenyl-silane,Ph4Si. II.

Vibrational spectra of Ph₄Si have been studied from 600 to 20 cm^?1 in solution, in the melt and in the crystalline state. The assignments proposed for the substituent sensitive benzene ring vibrations, for the skeletal bending modes and ring librations have been supported by polarized IR and Raman measurements. The crystal spectra are interpreted on the basis of the S₄ site symmetry of the molecules in the crystal. Two skeletal bending and four ring librational modes are supposed to appear below 120 cm^?1, in the range of the lattice vibrations.     

Temperature effects in the oxidation of aliphatic ketones by solutions of thallic sulfate

The oxidation of aliphatic ketones by thallium(III) sulfate in aqueous medium has been studied from the point of view of the temperature effect and the enthalpy-entropy relationship. It has been found that the isokinetic relationship is fulfilled in this case.

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(III) - . , .

     

Investigation of dehydration process,II

The dehydration of hydrated calcium and strontium bromides and iodides was studied by thermogravimetry and differential thermal analysis. The melting in the crystallization water was distinguished from the dehydration in a self-generated atmosphere. The results of the TG and DTA curves made simultaneously were verified by measurements with a Du Pont DSC apparatus. This latter investigation was extended to the previously studied chlorides too. Correlations were found between the temperature of melting or of dehydration and the ionic radii of the respective cations and anions.

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Zusammenfassung Die Dehydratisierung von Calcium- und Strontium-Bromid- und Jodidhydraten wurde mit den Methoden der Thermogravimetrie und Differentialthermoanalyse verfolgt. Das Schmelzen im Kristallwasser wurde von der Dehydratisierung in der selbsterzeugten Atmosphäre getrennt. Die Ergebnisse der simultan erhaltenen TG- und DTA-Kurven wurden durch Messungen mit einem Du Pont DSC-Gerät bestätigt, wobei die bereits schon untersuchten Chloride mit einbezogen wurden. Korrelationen zwischen den Schmelzoder Dehydratisierungstemperaturen und den Ionenradien der entsprechenden Kationen und Anionen werden beschrieben.

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Résumé Etude de la déshydratation des bromures et iodures de calcium et de Strontium hydratés par thermogravimétrie et par analyse thermique différentielle. La fusion dans l'eau de cristallisation a été distinguée de la déshydratation en atmosphère auto-générée. Les résultats des courbes TG et ATD obtenues simultanément ont été vérifiés par des mesures effectuées à l'aide d'un analyseur calorimétrique différentiel (DSC) Du Pont. L'étude a également été étendue aux chlorures précédemment étudiés. On propose des corrélations entre les températures de fusion ou de déshydratation et les rayons ioniques des cations et anions respectifs.

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Contribution à la phytochimie du genre Gentiana,VI. Etude des xanthones dans les feuilles de Gentiana bavarica L.

Ten tetraoxygenated xanthones (1-hydroxy-3, 7, 8-trimethoxyxanthone I; 1, 7-dihydroxy-3, 8-dimethoxyxanthone II; 1, 7, 8-trihydroxy-3-methoxyxanthone III; 1, 3, 7, 8-tetrahydroxyxanthone IV; 3, 7, 8-trimethoxyxanthone-1-O-primeveroside V; 7-hydroxy-3, 8-dimethoxyxanthone-1-O-primeveroside VI; 1, 8-dihydroxy-3-methoxyxanthone-7-O-acetylrutinoside VII; 7, 8-dihydroxy-3-methoxyxanthone-1-O-primeveroside VIII; 3, 7, 8-trihydroxyxanthone-1-O-primeveroside IX; 3, 7, 8-trihydroxyxanthone-1-O-glucoside X) have been isolated from leaves of Gentiana bavarica L . by means of column chromatography on polyamid. Among these xanthones, VI, VII, VIII and IX were not encountered before in nature.     

Use of the tubulin bound paclitaxel conformation for structure-based rational drug design

A new computational docking protocol has been developed and used in combination with conformational information inferred from REDOR-NMR experiments on microtubule bound 2-(p-fluorobenzoyl)paclitaxel to delineate a unique tubulin binding structure of paclitaxel. A conformationally constrained macrocyclic taxoid bearing a linker between the C-14 and C-3'N positions has been designed and synthesized to enforce this "REDOR-taxol" conformation. The novel taxoid SB-T-2053 inhibits the growth of MCF-7 and LCC-6 human breast cancer cells (wild-type and drug resistant) on the same order of magnitude as paclitaxel. Moreover, SB-T-2053 induces in vitro tubulin polymerization at least as well as paclitaxel, which directly validates our drug design process. These results open a new avenue for drug design of next generation taxoids and other microtubule-stabilizing agents based on the refined structural information of drug-tubulin complexes, in accordance with typical enzyme-inhibitor medicinal chemistry precepts.