Synthesis of substituted vinylgermanes and germylsilylethenes via ruthenium complex catalyzed germylation of olefins

A series of substituted vinylgermanes and divinylgermanes have been synthesized in moderate or high yield via two reactions of olefins and dienes catalyzed by [RuHCl(CO) (PCy₃)₂], i.e. germylative coupling with vinylgermanes and dehydrogenative germylation with hydrogermanes. While the former reaction can be a versatile way of regioselective synthesis of products (particularly useful for the stereoselective synthesis of germylsilylethenes), the latter could be used as a complement, especially in synthesis of germylate dioxol ethene and vinyl ethers. Copyright © 2008 John Wiley & Sons, Ltd.     

ADMET copolymerization of divinyltetraethoxydisiloxane with 1,9-decadiene catalyzed by Grubbs’ catalyst

The acyclic diene metathesis (ADMET) copolymerization of divinyltetraethoxydisiloxane with 1,9-decadiene, catalyzed by RuCl₂(=CHPh)(PCy₃)₂, is the first example of a siloxylene–vinylene–alkenylene copolymer reported in the literature. This copolymer was isolated and characterized by ¹H, and ¹³C NMR spectroscopy and GPC analysis (M_n=18 000, PDI=2.9).     

Indigocarmin,ein hochempfindliches Substrat in der Redox-Lösungskatalyse,insbesondere zum Nachweis von Mikrospuren sowie der katalytischen Eigenschaften organischer Verbindungen und Peroxysäuren

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Catalysis of Hydrosilylation. VIII. Addition of tri(chloro,methyl)silanes to vinyltri(chloro,methyl)silanes catalyzed by palladium phosphine complexes

Catalytic, synthetic, and analytical investigations of the hydrosilylation of vinyltri(chloro, methyl)silanes by tri(chloro, methyl)silanes in the presence of palladium phosphine complexes show the process to occur giving mostly 1,2-bis(silyl)ethanes (β-adducts) except in the case of all chloro substituents at both silicons of the substrates. The latter reaction was reported earlier [3] to give selectively 1,1-bis(trichlorosilyl)ethane (α-adduct). All results allow to propose a general scheme of the mechanism of catalysis of vinylsilane hydrosilylation by palladium phosphine complexes.     

Thermal analysis in evaluation of the radiochemical stability of some fungicidal drugs

Four azole derivatives showing antimycotic activity (Miconazole, Ketoconazole, Clotrimazole, Fluconazole) in solid phase were exposed to beta irradiation at the dose of 20-200 kGy and then alterations in the physicochemical properties of the above derivatives were studied using the methods: scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. It was found that the compounds irradiated with sterilising doses (20-50 kGy) showed no significant alterations in their physicochemical properties, while application of doses >50 kGy resulted in small changes in the X-ray diffraction patterns and in the course of DSC curves, including a decrease in the melting points and enthalpy of the process. For Miconazole and Fluconazole, a linear and relatively strong correlation was found (from r =0.9782 to r =0.9003) between the size of the dose of irradiation and the decrease in the melting point and enthalpy value. This revised version was published online in July 2006 with corrections to the Cover Date.     

Modification of (Poly)Siloxanes via Hydrosilylation Catalyzed by Rhodium Complex in Ionic Liquids

Summary. The hydrosilylation of 1-heptene, allyl glycidyl ether and, allyl polyether by heptamethylhydrotrisiloxane and poly(hydro, methyl)(dimethyl)siloxane catalyzed by rhodium(I) complexes (particularly [{Rh(μ–OSiMe₃)(cod)}₂]) in imidazolium ionic liquids (especially [TriMIM]MeSO₄) gives heptyl and glycidyloxy functional (poly)siloxanes and silicone polyethers with high yield and selectivity. The catalytic system based on rhodium siloxide can be easily separated from the product and successfully reused up to five times.     

Functionalization of octavinylsilsesquioxane by ruthenium-catalyzed silylative coupling versus cross-metathesis

Functionalization of octavinylsilsesquioxane (Vi(8)T(8), 1) by two reactions catalyzed by ruthenium complexes is reported: a silylative coupling reaction catalyzed by [RuHCl(CO)(PCy(3))(2)] (I) and cross-metathesis catalyzed by first- (II) and second-generation (III) Grubbs' catalysts. The two reactions of 1 with styrene take place highly regio- and stereoselectively (the X-ray structure of the product 2 has also been obtained); the cross-metathesis of 1-hexene and allyltrimethylsilane occurs quite effectively, whereas the silylative coupling with these compounds gives a mixture of isomers. Functionalization of 1 with heteroatom-substituted vinyl derivatives (Si, O, N) by silylative coupling reaction has been found to be highly efficient, but cross-metathesis appears to be the more effective method for the synthesis of S-substituted vinyl-silsesquioxane.     

Effect of oxidant on the reaction of [RhCl(cyclooctadiene)(phosphine)] with 1-hexene

Summary A promoting role of an oxidant, present in commercial 1-hexene, in the substitution of phosphine in the complex [RhCl(COD)(phosphine)] (1) where the phosphine is PPh₃ or 1/2 BPS-2 [bis(diphenylphosphinoethyl)tetra-methyldisiloxane] and COD=cycloocta-1,5-diene, has been detected and explained. When [oxidant]>[(1)] two reaction steps are distinguished: an oxidation of phosphine to phosphine oxide with generation of [RhCl(COD)], followed by its fast dimerization, and an oxidation of the dimer to Rh^III species. When [oxidant]<[(1)] the latter step is not observed and the reaction of [RhCl(COD)] with 1-hexene is favoured, particularly when an excess of phosphine (even at high oxidant concentration) is present. Most rate constants of the individual steps were evaluated.     

DSC study of radiostability of 1,4-dihydropyridine derivatives

The effect of sterilisation by irradiation has been studied for the seven most often used in medicine derivatives of 1,4-dihydropyridine (nifedipine, nisoldipine, nicardipine, nitrendipine, nimodipine, felodipine and amlodipine). The sterilisation was performed for the compounds in the solid phase with an electron beam of the energy 10 MeV, at room temperature, using the irradiation doses from 20 to 400 kGy. The effects of the irradiation were studied by the methods SEM, DSC, XRD and TLC. The sterilisation with doses 20-100 kGy was found to cause no changes in the physico-chemical properties of the compounds, while the irradiation with higher doses (200-400 kGy) was found to induce changes in the colour, DSC spectrum and TLC picture. As follows from the TLC results, the main product of radiolysis of the compounds studied was a pyridine nitrozoderivative, which indicates the same mechanism of decomposition as in the process of photodegradation. The results prove that the 1,4-dihydropyridine derivatives being highly sensitive to visible and UV radiation are generally resistant to ionising radiation and thus can be subjected to sterilisation by irradiation. This revised version was published online in July 2006 with corrections to the Cover Date.