Highly Enantioselective Cyanation of Aldehydes Catalyzed by a Multicomponent Titanium Complex
作者:Shaohua Gou、Xiaohong Chen、Yan Xiong、Xiaoming Feng
DOI:10.1021/jo060772z
日期:2006.7.1
new multicomponent bifunctional catalytic system based on a titanium complex was used for the efficient enantioselective cyanation of aldehydes. The catalyst was readily prepared from tetraisopropyl titanate (Ti(Oi-Pr)4), (S)-6,6‘-dibromo-1,1‘-bi-2-naphthol (1e), cinchonine (2a), and (1R,2S)-(−)-N-methylephedrine (3b). It was revealed that the combination of 1e, 2a, 3b, and Ti(IV) was essential in this
基于钛配合物的新型多组分双功能催化体系用于醛的有效对映选择性氰化。该催化剂易于由钛酸四异丙酯(Ti(O i -Pr)4),(S)-6,6'-dibromo-1,1'-bi-2-萘酚(1e),辛可宁(2a)和(1 R,2 S)-(-)- N-甲基麻黄碱(3b)。结果表明1e,2a,3b的组合在这种氰化反应中,Ti(IV)是必不可少的。在催化量的多组分催化剂的存在下,反应平稳进行,以中等至优异的分离产率(最高达95%)和高对映选择性(最高达94%ee)提供了所需的氰醇碳酸乙酯。提出了一种基于实验现象的催化循环来解释不对称感应的起源。