Effective activation of the chiral salen/Ti(OiPr)4 catalyst with achiral phenolic N-oxides as additives in the enantioselective cyanosilylation of ketones

被引：50

作者：

He, B ^{[1
]}

Chen, FX

Li, Y

Feng, XM

Zhang, GL

机构：

[1] Sichuan Univ, Coll Chem, Key Lab Green Chem & Technol, Minist Educ, Chengdu 610064, Peoples R China

[2] State Key Lab Appl Organ Chem, Lanzhou 730000, Peoples R China

[3] Chinese Acad Sci, Chengdu Inst Biol, Chengdu 610041, Peoples R China

来源：

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY | 2004年 / 2004卷 / 22期

关键词：

asymmetric catalysis; N-oxides; cyanosilylation; cyanohydrins;

D O I：

10.1002/ejoc.200400411

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

The activation of chiral titanium(IV) complexes with phenolic N-oxides additives has been found to provide an alternative strategy for 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. A catalytic cycle based on experimental phenomena and studies has been proposed to explain the origin of this activation and the asymmetric induction.

引用

页码：4657 / 4666

页数：10

共 51 条

[1] The effect of catalyst loading and donor ligands in the Mn(III) salen catalysed chiral epoxidation of chromenes: Synthesis of BRL 55834. [J].