Synthesis and preliminary cytotoxicity studies of achiral pyrrolyl-substituted titanocenes

From the reaction of various 6-pyrrolylfulvenes (3a–3d) with Super Hydride (LiBEt₃H), lithiated cyclopentadienide intermediates (4a–4d) were synthesised. These intermediates were then transmetallated with titanium tetrachloride TiCl₄ to yield the pyrrolyl-substituted titanocenes bis-[((1-(4-methoxybenzyl)-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride (5a), bis-[((1-(4-methoxyphenyl)-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride (5b), bis-[((2,4-bis(4-methoxyphenyl)-1-methyl-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride (5c), bis-[((2-(4-methoxyphenyl)-1-methyl-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride (5d). Titanocene 5b crystallised and was characterised by X-ray crystallography. The four titanocenes 5a–5d were tested for their cytotoxicity through MTT-based in vitro tests on CAKI-1 cell lines in order to determine their IC₅₀ values. Titanocenes 5a–5d were found to have IC₅₀ values of 440 (±35), 68 (±14), 105 (±30), and 36 (±7) μM.     

Phase behaviors of Gemini cationic surfactants/n-butanol/water systems

Phase diagrams for ternary system of the Gemini cationic surfactants, N,N-long chain alkyl-2-hydroxyl-N,N,N,N-tetramethyl diammonium dichloride (G_nCl₂) with butanol and water have been drawn based on experimental data at 25 °C. The phase diagrams show that L phase and different liquid crystalline phases are existent in the ternary system at different components. Electric conductivity of the L phase has been studied. Small-angle X-ray scattering (SAXS), ²H (deuterium) quadrupolar splitting (²H NMR) and the polarizing-light microscope were employed to confirm the characteristic texture structures and the microstructure of three different liquid crystalline phases.     

Determination of the titanium content of human transferrin by inductively-coupled plasma-atomic-emission spectroscopy

We report a simple method that combines dialysis, as a purification method, with the multielement capability of ICP to determine the titanium-to-transferrin mole ratio at physiological pH, under buffer conditions. The method, by means of which titanium and transferrin are determined simultaneously, enabled us to assess the binding capacities of different titanocene complexes. Figure Titanocene dichloride     

Antitumor activity of vanadocene Y and its selenocyanate derivative in xenografted caki-1 tumors in mice

The para-methoxybenzyl-substituted vanadocene dichloride (Vanadocene Y) (1) and its diselenocyanate (Selenocyanato-Vanadocene Y) (2) were tested in vitro in an anti-angiogenesis assay against human umbilical vein endothelial cells (HUVEC) delivering IC50 values of 0.92 ± 0.03 μM (1) and 37 ± 11 μM (2). In a cytotoxicity assay against the human renal cancer cells, CAKI-1, the compounds demonstrated IC50 values of 0.55 ± 0.09 μM (1) and 0.25 ± 0.03 μM (2). Then both compounds were given at their maximum tolerable dose, MTD, of 20 mg/kg/d (1) or 40 mg/kg/d (2) on four consecutive days or at 50% of the MTD on five consecutive days per week for three weeks to overall four cohorts of eight CAKI-1 tumor-bearing female NMRI:nu/nu mice each, while a further cohort was treated with solvent only. Both MTD-treated mouse cohorts showed a statistically significant tumor growth reduction with respect to the solvent-treated control group with an optimal T/C value of 47% on day 39 of the experiment. Immunohistological analysis revealed that the expression of the proliferation marker Ki-67 was reduced due to long-term treatment with 2.     

Effects of exposure to dibutyltin dichloride on sperm density,viability and morphology in male mice

Experiments on the effects of 0.025–0.40 µg of dibutyltin dichloride (DBTCl) per kilogram body weight (kg bw), on sperm density, viability and morphology in mature mice were conducted by daily intraperitoneal injection for 7 days at 22 ± 2 °C and 12 h light–dark cycle conditions. The results demonstrated that DBTCl exhibited strong toxicity on sperm quality. Dosed with ≥ 0.05 µg DBTCl/kg bw groups, the testes weight, sperm density and the rate of survival of sperm decreased, whereas the rate of sperm abnormalities increased significantly. In addition, treatment with 0.05 µg DBTCl/kg bw resulted in increasing rate of sperm head abnormalities, whereas administration at 0.20 and 0.40 µg DBTCl/kg bw significantly increased the rate of sperm tail abnormalities. In the group treated at ≥ 0.10 µg DBTCl/kg bw, the mice body weights decreased. It appeared there was a noticeable dose–response relationship between DBTCl and the parameters studied. ED₅₀ values (7 days) of DBTCl for survival rate of sperm and density were 0.17 µg/kg bw and 0.19 µg/kg bw respectively. The present study provides a possibility for early diagnostic indicators and methods for sperm quality induced by organotin compounds (DBTCl) in mammals. Copyright © 2001 John Wiley & Sons, Ltd.     

Allylstannation of α-, β- and γ-diketones mediated by allylbutyltin halides: Bu2(CH2=CHCH2) SnCl and Bu(CH2 =CHCH2) SnCl2

Butane-2,3- (1a), pentane-2,4- (1b) and hexane-2,5-dione (1c) react with Bu₂(CH₂=CHCH₂)SnCl in the presence of water to give monoallylated keto-ols (2a, 2b) and/or diallylated diols (3a, 3b, 3c), this depending upon the employed molar ratio [diketone]/[allyltin chloride]. Bu(CH₂=CHCH₂)SnCl₂ reacts with neat 1c in a one-pot synthesis to give mixtures of heterocyclic compounds: 2,5-diallyl-2,5-dimethyltetrahydrofuran (4), and 3-chloro-1,5-dimethyl-8-oxabicyclo [3,2,1] octane (5). Compound 4 is also obtained in high yield from the corresponding diol 3c by cyclodehydration promoted by RSnCl₃ (R = Me and Bu).     

有机镧系络合物[Li(THF)2]2(μ-Cl)4(η^5-C5H5)Ln.THF的合成

Manastyrskyj 等首次报道了重稀土环戊二烯二氯化物 C_5H_5L_nC(?)_2(Ln=Sm～Lu)的合成,但未得到相应的轻稀土环戊二烯基二氯化物。他们把这一结果归因于镧系收缩和配位不     

A novel method for the reduction of sulfoxides and pyridine N-oxides with the system silane/MoO2Cl2

A novel method for the reduction of sulfoxides and pyridine N-oxides using a silane and a catalytic amount of MoO₂Cl₂ in excellent yields and with a wide functional group tolerance is reported. A green protocol for this reaction was developed in water with the air-stable catalytic system PMHS/MoO₂Cl₂(H₂O)₂.     

Synthesis,structure and isomerism of “three-bridge” exo-nido-osmacarborane clusters

The reaction of OsCl₂(PPh₃)₃ with [nido-7-R¹-8-R²-C₂B₉H₁₀]K⁺ produced a series of new exo-nido-osmacarborane complexes exo-nido-5,6,10-[Cl(Ph₃P)₂Os]-5,6,10-(-H)₃-10-H-7-R¹-8-R²-7,8-C₂B₉H₆ (1: R¹ = R² = H; 2: R¹ = R² = Me; 3: R¹ = R² = PhCH₂; 4: R¹ + R² = 1,2-C₆H₄(CH₂)₂; 5: R¹ = H, R² = Me) in which the osmium-containing group is linked to the nido-carborane ligand through three two-electron three-center bonds. Compounds 1—5 are formed as mixtures of symmetric (a) and asymmetric (b) isomers; pure symmetric isomers 2a and 4a were isolated by fractional crystallization, and the mixture of isomers 3a, was quantitatively separated into individual compounds 3a and 3b by column chromatography on silica gel. Detailed analysis of the ³¹P{¹H}, ¹H, ¹¹B NMR spectra of 1a,b—5a,b and 2D ¹H-¹H{¹¹B} and ¹¹B{¹H}-¹¹B{¹H} NMR spectra of 3a and 3b was performed. The structures of isomers 2a and 4a were confirmed by an X-ray diffraction study. According to the NMR and X-ray diffraction data, the isomerism of exo-nido-complexes 1a,b—5a,b is actually the cis—trans-isomerism of ligand arrangement in the octahedral coordination of the Os atom.     

An ab initio and DFT study on the hydrolysis of carbonyl dichloride

Hydrolysis of carbonyl dichloride or phosgene (Cl₂CO) in gas phase has been investigated at Hartree–Fock, density functional and ab initio levels of theory. The effects of basis sets on the energetics of the reaction have also been explored. Calculations reveal that initially carbonyl dichloride and water form a weak complex and this complex can react further in two ways. In Path 1, water adds on to carbonyl dichloride across carbonyl bond in a concerted fashion to give dichloromethane diol, and this diol decomposes to form chloro formic acid by syn-1,2-elimination of HCl and forms CO₂ and HCl as final products. Path 2 is the concerted addition of water across carbon chlorine bond and elimination of HCl in a single step leading to the formation of chloro formic acid directly. This second path that skips the formation of dichloromethane diol is observed to be very low lying and hence is kinetically favored. Addition of second water molecule to the reacting system is found to catalyze the reaction by stabilizing the complex, intermediate and transition states and reduces the activation energy to 24.6 kcal mol⁻¹ compared to 29.9 kcal mol⁻¹ for a single water molecule.