Synthesis of <i>C</i><sub>1</sub>-Symmetric Chiral Secondary Diamines and Their Applications in the Asymmetric Copper(II)-Catalyzed Henry (Nitroaldol) Reactions
作者:Yirong Zhou、Junfang Dong、Fanglin Zhang、Yuefa Gong
DOI:10.1021/jo102124d
日期:2011.1.21
A small library of C1-symmetric chiral diamines (L1−L9) was constructed via condensing exo-(−)-bornylamine or (+)-(1S,2S,5R)-menthylamine with various Cbz-protected amino acids. Among them, ligand L1/CuCl2·2H2O complex (2.5 mol %) shows outstanding catalytic efficiency for Henry reaction between a variety of aldehydes and nitroalkanes to afford the expected products in high yields (up to 98%) with
的一小库Ç 1个( -对称的手性二胺L1 - L9)通过冷凝构建外型- ( - ) - bornylamine或(+) - (1小号,2小号,5 - [R)-menthylamine与各种Cbz-保护的氨基酸。其中,配体L1 / CuCl 2 ·2H 2O络合物(2.5 mol%)对多种醛和硝基烷之间的亨利反应显示出出色的催化效率,以高收率(高达98%)提供了预期的产物,具有出色的对映选择性(高达99%)和中度到良好的非对映选择性(直到90:10)。该方法耐空气和湿气,已被用于合成(S)-2-氨基-1-(3,4-二甲氧基苯基)乙醇(9),这是(S)-肾上腺素和(S)的关键中间体)-去甲肾上腺素。基于HRMS和L1 / CuCl 2的X射线衍射分析复杂的情况下,提出了一种过渡状态模型来解释不对称感应的起源。低的催化剂负载量,优异的收率和对映选择性,廉价的铜盐以及温和的反应条件使我们的催化体系实用化。