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961.
Doan Thi Mai H Gaslonde T Michel S Koch M Tillequin F Pfeiffer B Renard P Kraus-Berthier L Léonce S Pierré A 《Chemical & pharmaceutical bulletin》2004,52(3):293-297
A series of cis-1,2-dihydroxy-1,2-dihydrobenzo[b]acronycine diacid hemiesters and dicarbamates were prepared by acylation of cis-1,2-dihydroxy-6-methoxy-3,3,14-trimethyl-1,2,3,14-tetrahydro-7H-benzo[b]pyrano[3,2-h]acridin-7-one. The cytotoxicity of the dicarbamates depended on the steric hindrance of the esterifying groups at positions 1 and 2. Diacid hemiesters displayed significant in vitro cytotoxic activities and induced cell cycle perturbations similar to those obtained with cis-1,2-diacetoxy-1,2-dihydrobenzo[b]acronycine (S23906-1) currently under preclinical development. cis-1-Acetoxy-2-hemiglutaryloxy-1,2-dihydrobenzo[b]acronycine was the most promizing compound of the series, inducing complete inhibition of tumor growth when tested against C38 colon adenocarcinoma implanted in mice. 相似文献
962.
963.
Jean M. J. Tronchet Alain P. Bonenfant Franoise Perret Alberto Gonzalez Jean-Bernard Zumwald Ernesto M. Martinez Bruno Baehler 《Helvetica chimica acta》1980,63(5):1181-1189
Synthesis of Terminal Acetylenic Sugars Derivatives and Ynuronic Acids Derivatives by Use of a Wittig Reaction The method described for the preparation of terminal acetylenic sugars presents two advantages over earlier procedures: no new asymmetric center is created and the chain can be extended by one or more C-atoms. The method also allows preparation of ynuronic acids. The aldehydosugars derivatives 1–7 gave in good to excellent yields the corresponding gem-dibromoenoses 8–14 from which either the terminal acetylenic sugars derivatives 15–21 or the ynuronic acids 22–24 were easily prepared. A few examples of 1,3-dipolar cycloadditions (leading to 28–30 ) with these acetylenic sugar derivatives are also described. 相似文献
964.
Belaïd Diab Henri Jolibois Bernard Laude Stphane Golhen Lahcne Ouahab Alain Chambaudet 《Helvetica chimica acta》1999,82(5):779-789
One-Step Synthesis of Novel Heptacyclic Molecules Starting from 2-Aryl-4-methyl-1-benzopyrylium Salts. X-Ray Crystal Structures of These Compounds Containing a Methano-Bridged 1-Benzoxepine Fused to Two 1-Benzopyran Moieties The chemical reduction of 4-methyl-2-(ortho-hydroxyaryl)-1-benzopyrylium chlorides with Zn in MeCN and HCl led to a mixture of diastereoisomeric heptacyclic molecules. The structures of two of them were determined by X-ray analysis. These methano-bridged 1-benzoxepines fused to two 1-benzopyran moieties were formed from intermediate biflavene species. 相似文献
965.
Sunita Omprakash Yemul Omprakash Shrinivas Yemul Surendra Ponrathnam C. R. Rajan Alain Fradet 《Macromolecular rapid communications》1998,19(12):635-639
The synthesis of poly(thio- 1,4-phenylene) (PPS) at room temperature by the reaction of diphenyl disulfide with potassium persulfate (K2S2O8) in non-basic solvents, in the presence of trifluoromethanesulfonic acid, is reported. The reaction in chlorinated solvents, such as dichloromethane and tetrachloroethane, resulted in partial oxidation of sulfide to sulfoxide and sulfone. On the other hand, the polymerization proceeded well in nitrobenzene and the PPS formed was free of branches, crosslinks and thianthrene units. The molecular weight of the polymers formed in different solvents were in the range 2000–8000. The reaction proceeded under identical conditions with bis(2,6-dimethylphenyl) disulfide as well, but the polymer yield was lower. 相似文献
966.
Alain Krief Thierry Van Wemmel Martine Redon Willy Dumont Cathy Delmotte 《Angewandte Chemie (International ed. in English)》1999,38(15):2245-2248
The addition of elemental selenium to organolithium compounds 1 or organic selenates 2 gives organic diselenolates 3 . The reactions proceed by the insertion of two selenium atoms into the carbon–metal bonds or of one selenium atom into a selenolate. Evidence for the existence of n-butyldisilenol has also been obtained. 相似文献
967.
968.
We present an unsplit second-order finite difference algorithm for hyperbolic conservation laws in several variables. Although the method can be directly implemented for general hyperbolic systems, we focus in this article on reducing grid orientation effects in porous media flow. In particular, we consider miscible and immiscible displacement processes. Our main concern is to develop a scheme that can easily be implemented into existing standard finite-difference-based reservoir simulators as an option to be used if grid orientation effects occur. The principle of the scheme is to build a higher order scheme to reduce numerical dispersion and that does not split the spatial operator to reduce the effect of the grid orientation. Numerical results are presented, which show that the method presented here reduces the effect of the numerical dispersion to a level that minimizes the grid orientation effects in a computationally efficient manner. © 1996 John Wiley & Sons, Inc. 相似文献
969.
Alain Guyot 《先进技术聚合物》1996,7(2):61-66
Polypropylene is the polymer with the fastest-growing usage rate, owing to its low price combined with properties that have been improved over recent years. However, because it does not carry any functional groups, it has little interaction with useful components of many systems, and it is difficult to paint. Recently, a certain number of attempts have been made to modify this polymer, either through direct copolymerization with reactive monomers, or after chemical modification of the polymer itself or some of its copolymers. The paper is a review of these different approaches, with emphasis on two points: (a) the new possibilities offered by the metallocene family of catalysts and (b), the work carried out in the author's laboratory, based on various functionalizations of copolymers of propylene and dienes. 相似文献
970.