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991.
Rhenium Dicarbonyl‐Nitrosyl Complexes with Imidazole Different rhenium‐dicarbonyl‐nitrosyl complexes with imidazole (Im) as monodentate ligand have been synthesized and characterized, starting from [NEt4][ReCl3(CO)2(NO)] and [ReCl(μ?Cl)(CO)2(NO)]2. Whereas the complexes [ReCl2(Im)(CO)2(NO)] and [ReCl(Im)2(CO)2(NO)]+ were achieved in high yields, the complex [Re(Im)3(CO)2(NO)]2+ with three imidazole ligands could only be isolated after complete removal of all halide ions (with AgBF4) in low yield. The synthesis of a corresponding 99mTc‐dicarbonyl‐nitrosyl complex with imidazole opens a new perspective for such compounds as potential radiopharmaceuticals and alternatives to the already established 99mTc‐tricarbonyl complexes. 相似文献
992.
1 INTRODUCTION The assembly of coordination networks is a field of increasing interest[1~4]. Research along this line is induced by the idea that coordination networks have potential technological applications such as optoele- ctronic devices and microporous materials for shape and size separation and catalysis[5~7]. In this paper, there has been current interest in using polycarboxy- late as anion linking groups to support stable poly- meric coordination open frameworks with transition m… 相似文献
993.
Masayuki Inoue 《Tetrahedron》2003,59(30):5645-5659
Ladder-shaped polyether natural products show diverse biological activities with extreme potency. As the initial phase of detailed SAR studies of bioactive polyethers, we set out to construct structurally simple mimics. This paper details the divergent synthesis of 6-X-7-6 tetracycles (X=7, 8, or 9) starting from a simple 6-membered ether. Key reactions in the synthesis include (i) the direct formation of an O,S-acetal by the coupling of an alcohol with an α-chlorosulfide, (ii) the construction of a 7-membered ring by radical cyclization, and (iii) cyclization to the 7, 8 or 9-membered ring via a ring-closing metathesis reaction. The neutral reaction conditions of our strategy enable the synthesis of a wide variety of substrates. The results of this study can be applied for the rapid construction of artificial polyether compounds with diversified molecular shapes and sizes. 相似文献
994.
995.
ZHANG Gai LIANG Yong-Qing ZHANG Rong-Lan ZHANG Wei-Hai ZHAO Jian-She GUO Zhi-An 《结构化学》2005,24(7):783-789
A new quinazolinone compound 2,3-dihydro-2-(2-hydroxyphenyl)-3-phenylquinazolin-4(IH)-one 3 ([C2oH16O2N2]-C2H5OH, Mr = 362.42) and compound 2-(2-hydroxybenzylidene-amino)-N-phenyl-benzamide 2 (C2oH16O2N2, Mr = 316.34) were prepared from a precursor of 2-amino-N-phenyl-benzamide 1 (C13H12ON2, Mr = 212.25). Compound 3 was characterized by single-crystal X-ray diffraction analysis. The crystal belongs to orthorhombic,space group Pbca with a = 1.2889(11), b = 1.6170(14), c = 1.7729(15) nm, V= 3.695(6) nm^3, Z= 8, F(000) = 1536, Mr = 362.42, Dc = 1.303 g/cm^3, μ(MoKa) = 0.087 mm^-1, R = 0.0447 and wR= 0.0879. The crystal structure analysis indicates that the title compound has a two-dimensional network structure formed by hydrogen bonds and electrostatic interactions. 相似文献
996.
Michael Sax 《Tetrahedron》2005,61(1):205-211
A novel solid phase synthesis of 2-substituted 2,3-dihydropyridin-4(1H)-ones using Rinkamide-polystyrene-resin is described. The key step involves a hetero-Diels-Alder reaction of Danishefsky's diene with solid phase bound imines, which was carefully optimized. Using this method even ketones are transformed into 2,2-disubstituted dihydropyridones. 相似文献
997.
Aude Fayol 《Tetrahedron》2005,61(48):11511-11519
Three-component reaction of an α-isocyanoacetamide 7, an homoallylamine 8 and an aldehyde 9 in methanol at room temperature provides oxa-bridged tricycle 4 in good to excellent yield as a mixture of two separable diastereoisomers. In this one-pot multicomponent process, one C-N, one C-O and three C-C bonds are formed with concomitant creation of five asymmetric centers and three rings. Fragmentation of epoxy-tetrahydronaphthyridine 4 affords differentially substituted 5,6,7,8-tetrahydro-1,7-naphthyridine (5, 6) depending on the reaction conditions, providing thus additional structural diversity. A one-pot three-component synthesis of 5,6,7,8-tetrahydro-1,7-naphthyridine (6) from 7, 8 and 9 is also documented. 相似文献
998.
L-Nucleosides have attracted considerable attention since many analogs have exhibited a higher antiviral potency and selectivity than their corresponding D-isomers1. In particular, (-)-(2R, 5S)-1-[(2-hydroxymethyl)-oxathiolan-5-yl]cytosine (3TC, Lamivu- dine)2,its 5-fluoro analog [(-)-FTC, Coviracil]3 and (-)--L-2',3'-dideoxy-5-fluorocytidine (L-FddC)4 are in various stages of preclinical or clinical trials as anti-HIV and anti-HBV agents. Furthermore, the introduction of a 2'--fluo… 相似文献
999.
(+)-4-(1-Trimethylsilyloxyethen-1-yl)-2-carene was synthesized, and the products of its ozonization were identified.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1984–1987, October, 1995. 相似文献
1000.
2-Trifluoroacetyl-4,5-dihydrofurans were obtained by manganese(III) acetate mediated radical cyclization of trifluoromethyl-1,3-dicarbonyl compounds (1a-c) with conjugated alkenes (2a-h). The reaction of 1,1,1-trifluoropentane-2,4-dione (1a) with propenylbenzene and 1,1-diphenyl-1-butene surprisingly yielded 3-(dihydrofuran-2(3H)-ylidene)-1,1,1-trifluoroacetones besides 3-trifluoroacetyl-4,5-dihydrofurans. 相似文献