Regulation of the flexibility of planar chiral [2.2]paracyclophane ligands and its significant impact on enantioselectivity in asymmetric reactions of diethylzinc with carbonyl compounds
作者:Xun-Wei Wu、Tang-Zhi Zhang、Ke Yuan、Xue-Long Hou
DOI:10.1016/j.tetasy.2004.06.026
日期:2004.8
A series of planar chiral ligands derived from [2.2]paracyclophane were synthesized and applied as catalysts in enantioselective additions of diethylzinc to aldehydes and α,β-unsaturated ketones. When ligand 10 with a dimethyl hydroxymethyl as the substituent was used, the enantioselectivity of the reaction of diethylzinc with aldehydes was much higher than when using ligand 3c with diphenyl hydroxymethyl
合成了一系列衍生自[2.2]对环环烷的平面手性配体,并将其用作催化剂,将二乙基锌与醛和α,β-不饱和酮进行对映选择性加成。当使用具有二甲基羟甲基作为取代基的配体10时,二乙基锌与醛的反应的对映选择性比使用具有二苯基羟甲基作为取代基的配体3c的对映选择性高得多。当使用羟甲基取代的配体7b时,将二乙基锌1,4-加成到α,β-不饱和酮上时,情况相同,ee为63-83%,而如果使用配体3c,则几乎不提供对映选择性。还研究了平面手性的作用。