Chiral Macrocyclic Bis(oxazoline) CuI Complexes – Structure/Stereoselectivity Relationships in Catalytic Cyclopropanations
作者:Tomislav Portada、Marin Roje、Zlata Raza、Vesna Čaplar、Mladen Žinić、Vitomir Šunjić
DOI:10.1002/ejoc.200600827
日期:2007.2
complex represents a conceptually new type of supramolecular organometallic catalyst, possessing a chiral reaction cavity. A clear relationship between catalyst structures and the stereoselectivity outcome in the catalytic cyclopropanations has been established and it is demonstrated that both the enantioselectivity and the diastereoselectivity can be independently modified by variation of the ligand structural
描述了具有内置 C2 对称双 (恶唑啉) 单元的 18 个手性大环的设计和合成,并评估了它们的铜 (I) 配合物在苯乙烯与重氮乙酸乙酯环丙烷化中的催化性能。双(恶唑啉)单元中两个同手性中心的桥接产生了大环配体,其在与 CuI 结合后转化为包含手性空腔的大环催化复合物。这种配合物代表了一种概念上新型的超分子有机金属催化剂,具有手性反应腔。已经建立了催化环丙烷化中催化剂结构和立体选择性结果之间的明确关系,并且证明对映选择性和非对映选择性都可以通过配体结构参数的变化独立地改变。配体 3b 的 CuI 配合物产生 94:6 (de = 88%) 的反式/顺式非对映异构体比率,代表迄今为止由双(恶唑啉)类配合物催化的环丙烷化获得的最高非对映选择性。提出了对观察到的立体化学结果与配体结构之间关系的解释。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim