Increasing Enantioselectivities and Reactivities by Stereochemical Tuning: Fenchone-Based Catalysts in Dialkylzinc Additions to Benzaldehyde
作者:Bernd Goldfuss、Melanie Steigelmann、Frank Rominger
DOI:10.1002/(sici)1099-0690(200005)2000:9<1785::aid-ejoc1785>3.0.co;2-0
日期:2000.5
alcohols [(1R,2R,4S)-exo-(2-Ar)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol, Ar = 2-methoxyphenyl (1) and Ar = 2-(dimethylaminomethyl)phenyl (2)] yield the chiral ligands 3 [Ar = 2-methoxy-3-(trimethylsilyl)phenyl] and 4 [Ar = 2-(dimethylaminomethyl)3-(trimethylsilyl)phenyl]. Increased reactivities and enantioselectivities in diethylzinc additions to benzaldehyde are obtained from 3 (63% eeR) and 4 (93%
苯甲醇的三甲基甲硅烷基取代 [(1R,2R,4S)-exo-(2-Ar)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol,Ar = 2-甲氧基苯基 (1) 和Ar = 2-(二甲氨基甲基)苯基(2)]产生手性配体3[Ar = 2-甲氧基-3-(三甲基甲硅烷基)苯基]和4[Ar = 2-(二甲氨基甲基)3-(三甲基甲硅烷基)苯基]。相对于 1 (26% eeS) 和 2 (73% eeS),从 3 (63% eeR) 和 4 (93% eeS) 中获得增加的二乙基锌添加到苯甲醛中的反应性和对映选择性。3 及其甲基锌配合物 3-Zn 的 X 射线晶体结构揭示了甲氧基的平面外弯曲是三甲基甲硅烷基取代的主要几何结果。QM/MM ONIOM μ-O 过渡结构模型分析 1, 2, 3,