Enantioselectivity of chiral zirconocenes as catalysts in alkene hydro-, carbo- and cycloalumination reactions
作者:Lyudmila V. Parfenova、Tatyana V. Berestova、Tatyana V. Tyumkina、Pavel V. Kovyazin、Leonard M. Khalilov、Richard J. Whitby、Usein M. Dzhemilev
DOI:10.1016/j.tetasy.2010.01.001
日期:2010.3
and enantioselectivity. The reaction chemo- and enantioselectivity depend on the catalyst structure and reaction conditions (solvent type, catalyst concentration, temperature) as well. It is shown that the lack of asymmetric induction in the reaction of α-methylstyrene hydroalumination by HAlBu2i, catalyzed with complexes 1 or 3, is the result of the formation of Zr hydride complexes of different structures
手性Zr催化剂L 1 L 2 ZrCl 2 [L 1 = L 2 = 1-新薄荷烯(Ind ∗),1 ;的对映选择性。L 1 = Cp,L 2 = Ind ∗ 2;大号1 =的Cp,L 2 = 1- neomenthylindenyl-4,5,6,7-四氢茚基(CP *)3 ]在由有机铝化合物(OAC)(阿尔梅烯烃的加氢,碳环和cycloalumination 3,ALET 3,HAlBu2i)已被研究。发现OAC对反应的化学和对映选择性表现出最大的影响。反应的化学和对映选择性也取决于催化剂的结构和反应条件(溶剂类型,催化剂浓度,温度)。结果表明,配合物1或3催化HAlBu2i在α-甲基苯乙烯加氢铝化反应中没有不对称诱导。,是形成不同结构的Zr氢化物配合物作为反应中间体的结果。MTPA用作衍生试剂,用于对反应产物进行氧化和水解后获得的β-手性醇的对映体过量估计和绝对构型分配。显