Discreteversus In Situ-Generated Aluminum-Salen Catalysts in Enantioselective Cyanosilylation of Ketones: Role of Achiral Ligands
作者:Ali Alaaeddine、Thierry Roisnel、Christophe M. Thomas、Jean-François Carpentier
DOI:10.1002/adsc.200700565
日期:2008.3.25
been individually evaluated in the asymmetric cyanosilylation of acetophenone. It is shown that, in several cases, these discrete catalysts display dramatically different performances than the catalyst systems in situ-generated from the binary combinations. The influence of the achiral ligand X on both the enantioselectivity and activity of the cyanosilylation reaction has been investigated, resulting
单金属物种Salen} AlX(X = Me,2a,b ; X = Cl,4a,b ; O- i- Pr,5a,b)和开放双金属物种Salen} [AlMe 2 ] 2(3a,b)是由铝前体[三甲基铝,氯化二甲基铝,三(异丙醇)铝]和双旋Salen} H 2前配体1a,b(a = 1 R,2 R-环己基salen; b = 1 R,2 R-二苯基亚乙基-salen)已被分离。报道了3b,4b和μ-氧代[二苯基乙烯-salen} Al] 2 O(6b)的晶体结构。在苯乙酮的不对称氰基甲硅烷基化反应中已分别评估了离散物种2 – 5a,b。结果表明,在某些情况下,这些分立的催化剂与原位催化剂体系相比,表现出截然不同的性能。-由二进制组合生成。已研究了非手性配体X对氰基甲硅烷基化反应的对映选择性和活性的影响,从而为各种芳基烷基酮(TON最高至470,对于苯乙酮而言,TOF在-20°C下可达140