carbonyl group, cyano group) in an alkyl halide facilitates its cross-coupling reaction with various diorganozincs in the presence of Ni(acac)(2) (7.5-10 mol % in THF/NMP mixtures). These results were used to develop a new general cross-coupling reaction between functionalized diorganozincs and alkyliodides using m- or p-trifluoromethylstyrene as a reaction promotor and Ni(acac)(2) as a catalyst (7.5-10
A Mild and Efficient Chemoselective Protection of Primary Alcohols as Pivaloyl Esters Using La(NO<sub>3</sub>)<sub>3</sub>·6H<sub>2</sub>O as a Catalyst under Solvent-free Conditions
作者:P. Prabhakar、N. Suryakiran、Y. Venkateswarlu
DOI:10.1246/cl.2007.732
日期:2007.6.5
Primary alcohols are selectively and efficiently protected as their pivaloyl esters with pivaloyl chloride in the presence of catalytic amounts of La(NO3)3·6H2O at room temperature under solvent-free conditions in excellent yields.
A simple and highly efficient protocol for pivaloylation of alcohols without using a catalyst under solvent-free conditions has been developed. The key advantages of the reaction are short reaction time, high yields, simple workup, and no need for further purification. Selectivity was observed between primary alcohols vs. secondary alcohols and aliphatic alcohols vs. aromatic alcohols. The accentuated
Diverse Alkyl–Silyl Cross-Coupling via Homolysis of Unactivated C(sp<sup>3</sup>)–O Bonds with the Cooperation of Gold Nanoparticles and Amphoteric Zirconium Oxides
the degradation of polyesters and the synthesis of organosilanes were realized concurrently by the unique catalysis of supported gold nanoparticles. Mechanistic studies corroborated the notion that the generation of alkyl radicals is involved in C(sp3)–Si coupling and the cooperation of gold and an acid–base pair on ZrO2 is responsible for the homolysis of stable C(sp3)–O bonds. The high reusability and
Efficient deoxygenative silylation of C(sp3)–O bonds with hydrosilanes by supported Au catalysts is described. Goldnanoparticlessupported on TiO2 enabled various hydrosilanes to be used as sources of silyl groups in C–Si cross-coupling reactions. A variety of alkyl acetates and propargyl carbonates participated in the Au-catalyzed reactions to furnish the corresponding alkyl and allenylsilanes in
描述了负载型 Au 催化剂对 C(sp 3 )–O 键与氢硅烷的有效脱氧硅烷化。负载在 TiO 2上的金纳米粒子使各种氢硅烷能够在 C-Si 交叉偶联反应中用作甲硅烷基的来源。各种乙酸烷基酯和碳酸炔丙酯参与了金催化的反应,以高产率提供相应的烷基和烯丙基硅烷。此外,Au/TiO 2对环醚的开环甲硅烷基化也有效。详细的机理研究证实标题反应涉及甲硅烷基和烷基自由基中间体的形成,而 Au 纳米颗粒作为单电子转移催化剂与金属氧化物表面的路易斯酸位点的合作是氢硅烷异常反应性的原因特定的 C(sp 3 )–Si 键形成。