Acid-Base Combined Catalytic System for Enantioselective Reactions

本课题主要研究了手性刘易斯酸与碱催化剂的复合催化体系对光学活性酮亚胺钴配合物的催化作用。对酮亚胺配合物催化剂的中心金属进行了筛选，发现钴是合成吡喃酮衍生物的最有效的催化剂。开发了相应的阳离子钴（III）配合物作为有效的刘易斯酸催化剂，并进行了杂Diels-Alder反应和羰基-烯反应。结果表明，它们的抗衡阴离子对羰基-烯反应的反应活性和对映选择性有显著影响。该阳离子钴配合物可作为对映选择性1，3-偶极环加成反应的有效催化剂。由于硝酮的竞争配位作用，单齿α，β-不饱和醛与1，3-偶极环加成反应仅限于几种催化剂，尽管这些阳离子钴（III）配合物有效地催化了该反应，得到了具有高度至优异立体选择性的异恶唑啉衍生物。这些类型的钴络合物催化剂可以应用于甚至在胺碱存在下的对映选择性亨利反应，以及二氧化碳的对映选择性化学固定以获得光学活性环状碳酸酯。对3-氧代亚丁基氨基钴配合物催化的杂Diels-Alder反应的密度泛函计算表明，醛作为刘易斯碱的轴向配位在钴（III）催化循环中诱导了自旋跃迁.配合物的刘易斯酸性增加，对映选择性提高。

This project was focused on the combined catalytic systems of base catalysts and the chiral Lewis acid of the optically active ketoiminatocobalt complexes. It was reported that screening of the central metal of the ketoiminato complex catalysts for the enantioselective hetero Diels-Alder reaction revealed that cobalt was the most effective for affording the corresponding pyranone derivatives. The corresponding cationic cobalt(III) complexes were developed as an efficient Lewis acid catalyst and subjected to the hetero Diels-Alder reaction and the carbonyl-ene reaction. It was found that their counter anions significantly influenced the reactivity and the enantioselectivity in the carbonyl-ene reaction. The cationic cobalt(III) complexes could be employed as the efficient catalysts for the enantioselective 1,3-dipolar cycloaddition reaction. Because of the competitive coordination of the nitrone, the 1,3-dipolar cycloaddition with the monodentate α,β-unsaturated aldehyde has been limited to several catalyses, although these cationic cobalt(III) complexes effectively catalyzed the reaction to afford the isoxazoline derivative with high-to-excellent stereoselectivities. These types of cobalt complex catalysts could be applied to the enantioselective Henry reaction even in the presence of amine bases, and the enantioselective chemical fixation of carbon dioxide to obtain the optically active cyclic carbonate. Density functional calculations on the hetero Diels-Alder reaction catalyzed by 3-oxobutylideneaminatocobalt complexes revealed that axial coordination of an aldehyde as a Lewis base induce a spin transition in the cobalt(III) catalytic cycle. The Lewis acidity of the complex was increased and the enantioselectivity was improved.