Organocatalyzed Asymmetric 1,4-Addition of Azlactones to α,β-Unsaturated Trichloromethyl Ketones: Synthesis of α,α-Disubstituted α-Amino Acid Derivatives
作者:Jinlong Zhang、Xihong Liu、Chongyang Wu、Panpan Zhang、Jianbo Chen、Rui Wang
DOI:10.1002/ejoc.201403158
日期:2014.11
4-addition of azlactones to α,β-unsaturated trichloromethyl ketones catalyzed by cinchona alkaloid derived bifunctional thiourea catalysts was developed. A series of α,α-disubstituted α-amino acid derivatives bearing a quaternary stereocenter at the α-position were obtained in high yields with excellent diastereo- and enantioselectivities (up to -20:1 dr and 99% ee). In addition, the trichloromethyl moiety
开发了第一个由金鸡纳生物碱衍生的双功能硫脲催化剂催化的吖内酯与 α,β-不饱和三氯甲基酮的不对称 1,4-加成反应。以高产率获得了一系列在 α 位具有四元立体中心的 α,α-二取代 α-氨基酸衍生物,并具有优异的非对映选择性和对映选择性(高达 -20:1 dr 和 99% ee)。此外,这些加合物中的三氯甲基部分被确定为良好的离去基团。