A General Study of[(η5-Cp′)2Ti(η2-Me3SiC2SiMe3)]-Catalyzed Hydroamination of Terminal Alkynes: Regioselective Formation of Markovnikov and Anti-Markovnikov Products and Mechanistic Explanation (Cp′=C5H5, C5H4Et, C5Me5)
作者:Annegret Tillack、Haijun Jiao、Ivette Garcia Castro、Christian G. Hartung、Matthias Beller
DOI:10.1002/chem.200305674
日期:2004.5.17
A general study of the regioselective hydroamination of terminal alkynes in the presence of [(eta5-Cp)2Ti(eta2-Me3SiC2SiMe3)] (1), [(eta5-CpEt)2Ti(eta2-Me3SiC2SiMe3)] (CpEt=ethylcyclopentadienyl) (2), and [(eta5-Cp*)2Ti(eta2-Me3SiC2SiMe3)] (Cp*=pentamethylcyclopentadienyl) (3) is presented. While aliphatic amines give mainly the anti-Markovnikov products, anilines and aryl hydrazines yield the Markovnikov
[[eta5-Cp)2Ti(eta2-Me3SiC2SiMe3)](1),[(eta5-CpEt)2Ti(eta2-Me3SiC2SiMe3)](CpEt =乙基环戊二烯基)(参照图2),给出[(η5 -Cp *)2 Ti(η2 -Me 3 SiC 2 SiMe 3)](Cp * =五甲基环戊二烯基)(3)。脂族胺主要产生抗马尔可夫尼可夫产物,而苯胺和芳基肼则产生马尔可夫尼可夫异构体作为主要产物。有趣的是,使用脂肪族胺,例如正丁胺和苄胺,不同的催化剂导致观察到的区域选择性的显着变化。在这里,第一次简单地通过改变催化剂就观察到了从马尔可夫尼科夫产品到反马尔可夫尼科夫产品的高度选择性的转变。