Synthesis of substituted chiral chromans via organocatalytic kinetic resolution of racemic 3-nitro-2-aryl-2H-chromenes with ketones catalyzed by pyrrolidinyl-camphor-derived organocatalysts
作者:Dhananjay R. Magar、Kwunmin Chen
DOI:10.1016/j.tet.2012.05.019
日期:2012.7
pyrrolidinyl-camphor derivative 2b as a bifunctional organocatalyst under neat conditions in the presence of AcOH at 0 °C. In general, the organocatalytic asymmetric Michael addition of ketones proceeded smoothly to give the functionalized Michael adducts (3a–n) with good-to-high diastereo- and enantioselectivities (up to 92:8 dr, 93% ee, and 47% yield). The less reactive chromenes (S)-1a–h, k, l and (R)-1i–j were
在0°C存在AcOH的纯净条件下,使用吡咯烷基-樟脑樟衍生物2b作为双功能有机催化剂,探索了外消旋的2-芳基-3-硝基-2 H-苯甲基(1a – l)的动力学拆分。通常,酮的有机催化不对称迈克尔加成反应顺利进行,从而使官能化迈克尔加合物(3a - n)具有良好至高的非对映体和对映体选择性(高达92:8 dr,93%ee和47%的收率) 。活性较低的色烯(S)-1a – h,k,l和(R)-1i–以高化学产率和中等光学纯度(高达42%的化学产率和72%的ee)回收了j。