Nucleophilicity of Alkyl Zirconocene and Titanocene Precatalysts, and Kinetics of Activation by Carbenium Ions and by B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>
tritylium ions, and triarylborane B(C6F5)3 were measured spectrophotometrically. The rate constants correlate linearly with the electrophilicity parameter E of the benzhydrylium and tritylium ions employed, allowing us to determine the σ‐nucleophilicities of the metal–carbon bond of several zirconocenes and titanocenes. Bridging, substitution, metal, and ligand effects on the rates of metal–alkyl
分光光度法测定了苯甲酸铵离子,三苯甲基离子和三芳基硼烷B(C 6 F 5)3活化甲基和苄基金属茂预催化剂的动力学。速率常数与亲电参数E线性相关苯甲酰和三苯甲酰离子的数量,使我们能够确定几种锆茂和钛茂金属的金属-碳键的σ亲核性。研究了桥接,取代,金属和配体对金属-烷基键裂解速率(M = Zr,Ti)的影响,并利用结构-反应性相关性预测了茂金属离子对的生成动力学,茂金属离子对是其中的活性催化剂。并在受阻的路易斯对催化中是高度亲电的路易斯酸。
Structure and Reactivity of Boron-Ate Complexes Derived from Primary and Secondary Boronic Esters
作者:Kathryn Feeney、Guillaume Berionni、Herbert Mayr、Varinder K. Aggarwal
DOI:10.1021/acs.orglett.5b00918
日期:2015.6.5
Boron-ate complexesderivedfrom primary and secondary boronicesters and aryllithiums have been isolated, and the kinetics of their reactions with carbenium ions studied. The second-order rate constants have been used to derivenucleophilicity parameters for the boron-ate complexes, revealing that nucleophilicity increased with (i) electron-donating aromatics on boron, (ii) neopentyl glycol over pinacol
AbstractA transition‐metal‐free intermolecular coupling reaction of halocompounds with styrenes in the presence of NaH and 1,10‐phenanthroline was developed. This reaction afforded hydrocarbonated products with complete anti‐Markovnikov selectivity. The method allows the use of a wide range of halocompounds, including aryl and alkyl halides, and good functional group tolerance. Detailed mechanistic studies indicated that an anilide anion generated in situ by the NaH‐mediated reduction of 1,10‐phenanthroline works as an electron donor and a hydrogen source.