在25°C的乙腈水溶液和丙酮水溶液中测定了对位取代的三苯甲基(三苯甲基)乙酸酯,苯甲酸酯和对硝基苯甲酸酯的电离速率。常规和停止流技术已用于评估速率常数,范围为1.38×10 -5到2.15×10 2 s -1通过电导和光度法。不同取代的三苯甲基离子的不同稳定性说明了反应机理的逐渐变化。弱稳定的碳阳离子通过其共价前体的电离缓慢生成,并被水快速捕获。更好稳定的碳正离子会更快地生成并积累,因此在单个实验中可以将水的电离和捕获作为单独的步骤进行观察。最后,高度稳定的tr离子不会与水反应,只能测量其形成速率。电离速率常数与Winstein的电离功率Y线性相关。低坡度(0.17 < m<0.58)表示非类碳化过渡状态。尽管对于对称取代的三苯甲基衍生物,电离速率与Hammett-Brown的σ +参数之间的相关性极好,但观察到非对称取代的系统的偏差。电离速率(log k ion)和水溶液中碳正离子的稳定性(p
Lead Optimization Providing a Series of Flavone Derivatives as Potent Nonsteroidal Inhibitors of the Cytochrome P450 Aromatase Enzyme
摘要:
Following our SAR studies on aromatase inhibitors, new compounds were designed by appropriately modifying the structure of flavone 1 using our previously reported CoMFA model. While the introduction of substituents on the 2-phenyl ring alone did not cause improvement in potency, these modifications and the removal of the 7-methoxy group led to compounds showing inhibitory activity in the nanomolar range, comparable to the marketed drug fadrozole.
The Sensitive Balance between Five-Coordinate Carbene and Six-Coordinate Carbyne Ruthenium Complexes Formed from Ruthenium Vinylidene Precursors
作者:Pablo González-Herrero、Birgit Weberndörfer、Kerstin Ilg、Justin Wolf、Helmut Werner
DOI:10.1021/om010422x
日期:2001.8.1
carbene complexes [Ru(κ2-O2CR1)C(CH2Ph)OC(O)R2}(PiPr3)2]BArf [R1 = R2 = CHF2 (7a), CF3 (7b); R1 = CF3, R2 = H (7c)] were obtained on protonation of the precursors [Ru(κ1-O2CR1)(κ2-O2CR2)(CCHPh)(PiPr3)2] (4a−c) with [H(OEt2)2]BArf. Both 7a and 7b undergo a fluxional process in solution resulting in a κ1/κ2 interconversion of the carboxylato groups. The crystal and molecularstructures of 2b, 5e, and 6a
二氯(亚乙烯基)钌化合物[RuCl 2(C CHR)L 2 ](R = Ph或t Bu和L = PCy 3或P i Pr 3)(1a - d)与[H(OEt 2)2 ] BAR ˚F(巴˚F - = [B C 6 H ^ 3(CF 3)2 -3,5} 4 ] - )导致质子的在C攻击β亚乙烯基配体的碳原子,并以几乎定量的产率得到相应的阳离子,五配位碳氮鎓络合物[RuCl 2(⋮CCH 2 R)L 2 ] BAr f(2a - d)。所述羧酸根衍生物将[RuCl(κ的质子化2 -O 2 CR)(Ç CHPh配合)(P我镨3)2 ] [R = H(图3a),CH 3(图3b),或PH(3F)]与[ H(OET 2)2 ] BAR ˚F导致形成五配位环状卡宾配合物[RuCl C(CH 2 Ph)OC(O)R}(P i Pr 3)2 ] BAr f [R = H(6a),CH 3(6b) ,
Practical Preparation of Esters and Thioacetates from Alkyl Halides and Carboxylates or Thioacetate Catalyzed by PEG400 without Solvent
Abstract Carboxylic esters and thioacetates were conveniently prepared in good to excellent yields under mild conditions by the reaction of alkyl halides with sodium carboxylates or sodium thioacetate catalyzed by PEG400 in the absence of solvents.
Palladium-Catalyzed Cross-Coupling Reactions of Carboxylic Anhydrides with Organozinc Reagents
作者:Donghui Wang、Zhaoguo Zhang
DOI:10.1021/ol035801w
日期:2003.11.1
[reaction: see text] Negishi-type cross-coupling reaction was effected by employing organozincs and anhydrides or mixedanhydrides that formed in situ fromsodiumsalts of the corresponding acids and ethyl chloroformate under the catalysis of palladium(0). A general method for preparing symmetrical/unsymmetrical ketones was developed.
The syntheses of 32 complexes of the type (η-C5H5)2Ti(OOCC6H4X)2 are reported together with their mass, 1H NMR, 13C NMR, mid- and far-IR spectra. The data are consistent with a model in which the TiOOC bond strength (weaker than that of TiCp and TiHal) is stabilized by electron-withdrawing substituents X on the phenyl rings. The electronic influence of X also extends into the cyclopentadienyl rings
的类型的32种复合物的合成(η-C 5 H ^ 5)2的Ti(OOCC 6 H ^ 4 X)2与它们的质量,一起报告1 H NMR,13 C NMR,中期和远红外光谱。该数据与通过苯环上的吸电子取代基X稳定了TiOOC键强度(比TiCp和TiHal的强度弱)的模型一致。X的电子影响也延伸到环戊二烯基环中。
Synthesis and some reactions of tris (pentafluorophenyl) antimony compounds
Abstract (C6F5)3Sb has been found to react with interhalogens and halo-pseudohalogens, IX(X = Cl, Br, N3 and NCO), pseudohalogen (SCN), and elemental sulphur to give oxidative addition products (I–VI). (C6F5)3SbS(VI) may also be prepared by the reaction of (C6F5)3SbCl2 with H2S. Metathetical reactions of (C6F5)3SbCl2 with appropriate metallic salts yield covalent pentacoordinate disubstituted products