A Convenient Synthesis of Phosphorines and Phospholidins by <Emphasis Type="Italic">Lawesson</Emphasis>’s Reagent and Microwave Irradiation

Summary. A new and simple method for the synthesis of 1,3,2-diazaphosphorines and 1,3,2-oxazaphosphorine was developed based on the reactions of Lawessons reagent with -aminopropionitriles and -hydroxypropionitrile. In addition, a rapid and facile synthesis of 1,3,2-diazaphospholidin-4-ones by the reaction of P(NEt₂)₃ with hindered diamino substrates under microwave irradiation was also achieved. The prepared phosphorines show herbicidal activity to some extent in the preliminary bioassays.     

Polyfluorinated hydrazones in organic syntheses

The reaction of poly- and perfluoroaldehyde hydrazones with hydrazine hydrate was studied. A new preparative method for obtaining the hitherto inaccessibleN,N-unsubstituted bis-hydrazones of polyfluorinated -oxoaldehydes was developed based on this reaction.For Part 2, seeIzv. Akad. Nauk, Ser. Khim., 1995, 2465 [Russ. Chem. Bull, 1995,44, 2360 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2526–2527, December, 1995.This study was financially supported by the Russian Foundation for Basic Research (Grant No. 94-03-08548) and the International Science Foundation (Grant Nos. NDL 000 and NDL 300).     

Effect of hydrogen bonding of solvent on the thermodynamic stability of cadmium ethylenediamine complexes

Changes in the stability of the cadmium(ii) ethylenediamine complexes in mixed water—DMSO solvents were studied by pH-metry and calorimetry. Complex cations [Cd(en)]²⁺, [Cd(en)₂]²⁺, and [Cd(en)₃]²⁺ are formed in aqueous solutions, and the [Cd(en)₄]²⁺ complex with a partially dentate ligand is stable in DMSO. An increase in the DMSO content in a solvent increases the stability of the complexes. The maximum increase in logK is observed for coordinatively saturated compounds. The thermodynamics of complexation is discussed from the viewpoint of solvation approach. Principal differences in the influence of aqueous-alcohol and aqueous-aprotic solvents on the stability of the metal amino complexes were revealed. Protolytic solvents exert a destabilizing effect on the multiligand complexes, because the coordination sphere is involved in H bonding.     

Ligand-protein docking using a quantum stochastic tunneling optimization method

A novel hybrid optimization method called quantum stochastic tunneling has been recently introduced. Here, we report its implementation within a new docking program called EasyDock and a validation with the CCDC/Astex data set of ligand-protein complexes using the PLP score to represent the ligand-protein potential energy surface and ScreenScore to score the ligand-protein binding energies. When taking the top energy-ranked ligand binding mode pose, we were able to predict the correct crystallographic ligand binding mode in up to 75% of the cases. By using this novel optimization method run times for typical docking simulations are significantly shortened.     

Phytoecdysteroids of Plants of the Silene Genus. 2-Deoxyecdysterone-25-Acetate from Silene wallichiana

The new ecdysteroid 2-deoxyecdysterone-25-acetate was isolated from roots of Silene wallichiana Klotzsch.     

Hydration scheme of uracil and cytosine

The comparison of a pure electrostatic approximation and complete supermolecule SCF ab initio computations on the hydration scheme of uracil and cytosine shows that the electrostatic procedure is capable to reproduce the general aspects of the results of the supermolecule treatment provided that different distances of shortest approach be adopted for the distances between the oxygen of water and the nitrogen of NH₂ or NH groups or the oxygen of C-O groups on the one hand and the oxygen of water and pyridine-type nitrogens on the other hand.     

Metal Ion Guest Responsive Benzoxazine Dimers and Inclusion Phenomena of Cyclic Derivatives

This study was carried out with the aim to optimize the dissolution propertiesof diclofenac (DIC) – a non-steroidal anti-inflammatory drug sparingly solublein water – through association -with -cyclodextrin (CD). Theeffect of CD on the aqueous solubility of DIC was evaluated by thephase solubility method. The amount of DIC dissolved increased linearly withthe addition of CD according to an AL type plot and without precipitationof the complex. The apparent stability constant of the complex, calculated supposinga 1:1 stoichiometry, was 295 M^-1; this value was confirmed by circulardichroism analysis. DIC/CD interactions were also studied in water by¹H and ¹³C NMR spectroscopy. Equimolar DIC/CD solid systems were prepared by physical-mixing, kneading, co-evaporation andfreeze-drying, and their properties in the solid state studied by DifferentialScanning Calorimetry, X-ray powder diffractometry and Fourier-TransformInfrared analysis. For sake of comparison, the mixture of DIC and CDseparately lyophilized was investigated too. The results demonstrated that thefreeze-dried product had the highest degree of amorphization and they were inagreement with the existence of an inclusion complex in the solid state. Thedissolution profiles of the drug from each solid system were affected by its physico-chemical properties, the freeze-dried being the most rapidly dissolvingforms.     

Fe(0)催化三氯乙酸烯丙酯的环化反应研究

通过对Fe(O)催化烯烃自由基环化反应的研究，发现以Fe(O)为催化剂催化三氯 乙酸烯丙酯分子内自由基环化反应可以高化学选择性得到五元环内酯产物，反应中 不需加入配体。和大多数自由基反应一样，反应温度与催化剂用量对该反应的转化 率和产率有着很大的影响。     

Synthesis and fluorination of nitro-substituted thionocarbonates

Thiocarbonylchloride reacts with -nitroalcohols yielding symmetrical thionocarbonates. Transesterification of bis(2-fluoro-2,2-dinitroethyl)thioncarbonate affords alkyl 2-fluoro-2,2-dinitroethylthionocarbonates. Fluorination of these thionocarbonates yields the corresponding difluoroformals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 375–376, February, 1993.     

以短链季铵盐/脂肪酸盐为模板合成超微孔二氧化硅

超微孔材料具有1~2 nm的孔径,在分离、催化应用中有望展现出择形催化的能力。 寻找经济、简便的合成超微孔材料的表面活性剂体系是一项有意义的工作。 本研究以短链季铵盐(十烷基三甲基溴化铵,记为C₁₀TAB)和不同链长脂肪酸酸盐混合胶束为模板剂,硅酸钠为硅源,成功制备出高度有序超微孔SiO₂。 通过小角X射线衍射、N₂吸附-脱附、傅里叶变换红外光谱、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等技术手段对产品的结构和性能进行了表征。 结果表明,合成体系中脂肪酸盐碳链长、加入量、晶化温度等对产物孔道有序性有很大影响。 当选择正辛酸钠(SO)为助表面活性剂,当n(C₁₀TAB):n(Na₂SiO₃):n(SO):n(H₂O)=1:1.5:0.3:800,晶化温度为80 ℃时,可以得到高度有序超微孔SiO₂。 煅烧后样品比表面积为1300 m²/g,孔体积0.49 cm³/g,孔径分布在1.90 nm。