A micro-environment tuning approach for enhancing the catalytic capabilities of lanthanide containing polyoxometalate in the cyanosilylation of ketones
The well‐defined three coordinated electronically unsaturated cationic organoaluminum complex [((2,6‐iPr2C6H3N)P(Ph2)}2N)AlMe]+[MeB(C6F5)3]− (1), has been utilized to catalyze the cyanosilylation of aldehydes and ketones undermild and solvent‐free conditions. Moreover, catalyst 1 showed high chemoselective cyanosilylation of aldehydes over ketones, nitriles and olefins. The multinuclear NMR investigations
定义明确的三配位电子不饱和阳离子有机铝络合物[[(2,6 - i Pr 2 C 6 H 3 N)P(Ph 2)} 2 N)AlMe] + [MeB(C 6 F 5)3 ] −(1)已用于在温和无溶剂条件下催化醛和酮的氰基硅烷化反应。此外,催化剂1显示醛在酮,腈和烯烃上的高化学选择性氰基硅烷化。该多核NMR调查显示经由之间路易斯加成物形成的是硅氰化反应进行1 然后激活TMSCN(Si-CN键),然后在活化硅烷的Si中心对羰基氧进行亲核攻击并形成产物。
Inorganic/Organic Salts as Heterogeneous Basic Catalysts for Cyanosilylation of Carbonyl Compounds
作者:Xiaoming Feng、Bin He、Yan Li、Guolin Zhang
DOI:10.1055/s-2004-829569
日期:——
The addition of TMSCN to carbonyl compounds catalyzed by K2CO3 as heterogeneous catalyst gave the corresponding cyanohydrin trimethylsilyl ethers from 20 minutes to 24 hours with 62% to 99% yields without solvent at room temperature. Moreover, it was found that chiral organic salts as heterogeneous catalysts also can catalyze the asymmetric version and afford the corresponding products with up to 99% yield and 12.4% ee.
A highlyefficient cyanosilylation protocol mediated by the easily available n-BuLi with a wide range of aldehydes and ketones was developed. This protocol features excellent yields with very low n-BuLi loadings (0.01–0.05 mol%) at room temperature, solvent-free process, good chemo-/regio-selectivity and functional group tolerance and scalability. A possible reaction pathway based upon stoichiometric
Effective Activation of the Chiral Salen/Ti(OiPr)4 Catalyst with Achiral PhenolicN-Oxides as Additives in the Enantioselective Cyanosilylation of Ketones
the asymmetric cyanosilylation of ketones. By using 10 mol % of chiral salen-titanium(IV) complex in combination with 1 mol% achiral phenolic N-oxide as an additive, aromatic, aliphatic and heterocyclic ketones have been converted into the corresponding cyanohydrin trimethylsilyl ethers in 58-96% yields with 56-82% ee. Several factors concerning the reactivity and enantioselectivity have been discussed
catalysis promises high catalytic efficiency in the enantioselectivecyanosilylation of ketones through the combined use of a Lewis acid and a Lewis base. Catalyst systems composed of a chiral salen-Al complex and an N-oxide have high catalytic turnovers (200 for aromatic ketones, 1000 for aliphatic ones). With these catalysts, a wide range of aliphatic and aromatic ketones were converted under mild