Bis(((S)-binaphthoxy)(isopropoxy)titanium) oxide as a μ-oxo-type chiral Lewis acid:: Application to catalytic asymmetric allylation of aldehydes
Bis(((S)-binaphthoxy)(isopropoxy)titanium) oxide as a μ-oxo-type chiral Lewis acid:: Application to catalytic asymmetric allylation of aldehydes
复制标题
DOI：
10.1021/ja020338o
复制
发表时间：
2003-02-19
影响因子：
15
通讯作者：
Maruoka, K
中科院分区：
文献类型：
--
作者：
Hanawa, H;Hashimoto, T;Maruoka, K
成功地设计了一种新型的手性双钛（IV）氧化物1，它可以用于醛羰基化合物的强活化，从而使烯丙基三丁基锡催化醛的不对称烯丙基化反应成为可能.手性双Ti（IV）催化剂（S，S）-1可以通过用（S）-联萘处理双（三异丙氧基）氧化钛或通过（（S）-联萘氧基）异丙氧基氯化钛与银（I）氧化物反应容易地制备。氢化肉桂醛与烯丙基三丁基锡的反应（1.1当量）在原位生成的手性双-Ti（IV）氧化物（S，S）-1（10 mol %）在CH 2Cl 2中于0 ℃反应4 h得到1-苯基-5-己烯-3-醇，产率为84%，ee为99%。联萘啶在烯丙基化产物的对映体纯度与（S）-联萘啶的ee之间呈现正的非线性效应。这种不对称方法提供了一种非常有用的方法，通过在手性刘易斯酸催化剂的设计中简单地引入M−O−M单元来获得高的反应性和选择性。
A new, chiral bis-Ti(IV) oxide of type1was successfully designed and can be utilized for strong activation of aldehyde carbonyls, thereby allowing a new catalytic enantioselective allylation of aldehydes with allyltributyltin. The chiral bis-Ti(IV) catalyst (S,S)-1can be readily prepared either by treatment of bis(triisopropoxy)titanium oxide with (S)-binaphthol or by reaction of ((S)-binaphthoxy)isopropoxytitanium chloride with silver(I) oxide. Reaction of hydrocinnamaldehyde with allyltributyltin (1.1 equiv) under the influence of in situ generated chiral bis-Ti(IV) oxide (S,S)-1(10 mol %) in CH2Cl2at 0 °C for 4 h afforded 1-phenyl-5-hexen-3-ol in 84% yield with 99% ee. The present asymmetric allylation using nonracemic bis-Ti(IV) oxide1with partially resolved (S)-binaphthol exhibits a positive nonlinear effect in correlating the enantiopurity of allylation product with the ee of (S)-binaphthol. This asymmetric approach provides a very useful way for obtaining high reactivity and selectivity by the simple introduction of the M−O−M unit in the design of chiral Lewis acid catalysts.