Zhao Dongbo, Oisaki Kounosuke, Kanai Motomu, Shibasaki Masakatsu
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
J Am Chem Soc. 2006 Nov 15;128(45):14440-1. doi: 10.1021/ja0652565.
A general catalytic asymmetric reductive aldol reaction of allenic esters to ketones is described. Two distinct constitutional isomers were selectively produced depending on the reaction conditions. A combination of CuOAc/(R)-DTBM-SEGPHOS/PCy3 as the catalyst predominantly produced gamma-cis-products in high yield with excellent enantioselectivity (up to 99% ee). The reaction was applicable to both aromatic and aliphatic ketones, including unsaturated ketones. On the other hand, CuF-Taniaphos complexes produced alpha-aldol products with high diastereo- and enantioselectivity (up to 84% ee). The new Taniaphos derivative L3, containing di(3,5-xylyl)phosphine and morpholine units, produced optimum results in the alpha-selective reaction. The products are versatile chiral building blocks in organic synthesis. Furthermore, the basic reaction pattern (i.e., conjugate addition-aldol reaction) was extended to a catalytic enantioselective alkylative aldol reaction to ketones using dialkylzinc reagents as the initiator.
本文描述了一种将联烯酸酯与酮进行的通用催化不对称还原羟醛反应。根据反应条件,可选择性地生成两种不同的构造异构体。以醋酸铜/(R)-DTBM-SEGPHOS/三环己基膦作为催化剂,主要以高收率和优异的对映选择性(高达99%ee)生成γ-顺式产物。该反应适用于芳香族和脂肪族酮,包括不饱和酮。另一方面,CuF-塔尼磷配合物能以高非对映选择性和对映选择性(高达84%ee)生成α-羟醛产物。含有二(3,5-二甲苯基)膦和吗啉单元的新型塔尼磷衍生物L3在α-选择性反应中产生了最佳结果。这些产物是有机合成中通用的手性砌块。此外,基本反应模式(即共轭加成-羟醛反应)被扩展到使用二烷基锌试剂作为引发剂的催化对映选择性烷基化羟醛反应。