Stereochemical Consequences of Threefold Symmetry in Asymmetric Catalysis: Distorting C3 Chiral 1,1,1-Tris(oxazolinyl)ethanes (“Trisox”) in CuII Lewis Acid Catalysts
作者:Carole Foltz、Björn Stecker、Guido Marconi、Stéphane Bellemin-Laponnaz、Hubert Wadepohl、Lutz H. Gade
DOI:10.1002/chem.200701085
日期:——
trisox-copper complex [Cu(II)(iPr(3)-trisox)(kappa(2)-O,O'-MeCOCHCOOEt)](+)[BF(4)](-) (1), which was characterised by X-ray diffraction, two of the oxazoline groups are coordinated to the central copper atom, whilst the third oxazoline unit is dangling with the N-donor pointing away from the metal centre. A similar arrangement is found for the stereochemically "mixed" C(1)-trisox complex [Cu(II)(Ph(3)-trisox(R
在对含铜(II)的双恶唑啉(BOX)和三(恶唑啉基)乙烷(trisox)的催化性能的比较研究中,解决了在设计用于不对称催化的手性配体时利用两重和三重旋转对称性的根本概念差异。路易斯酸催化剂。通过反转手性中心或用非手性恶唑啉取代手性,系统地“变形”立体定向配体,在构造新催化剂时,差异变得显而易见。2-甲基乙酰乙酸乙酯与偶氮二苄基二苄基酯的催化α胺化反应被用作测试反应,该反应对Ph(2)-BOX和Ph(3)-trisox铜催化剂均具有高对映选择性。在三氧化铜复合物[Cu(II)(iPr(3)-trisox)(kappa(2)-O,O'-MeCOCHCOOEt)](+)[BF(4)](-)(1)中,X射线衍射的特征是,恶唑啉基团中有两个与中心铜原子配位,而第三个恶唑啉单元则悬空,而N供体背离金属中心。对于立体化学“混合”的C(1)-三tri络合物[Cu(II)(Ph(3)-trisox(R,S,S)}(κ(2)-O,O'-