Cooperative Activation of Alkyne and Thioamide Functionalities; Direct Catalytic Asymmetric Conjugate Addition of Terminal Alkynes to α,β-Unsaturated Thioamides
作者:Ryo Yazaki、Naoya Kumagai、Masakatsu Shibasaki
DOI:10.1002/asia.201100050
日期:2011.7.4
revealed that the intermediate copper‐thioamide enolate functioned as a Brønsted base to generate copper alkynylide from the terminal alkyne, thus driving the catalytic cycle through an efficient proton transfer between substrates. These findings led to the identification of a more convenient catalyst using potassium hexamethyldisilazane (KHMDS) as the Brønsted base, which was particularly effective for
详细描述了将末端炔烃直接催化不对称共轭加成至α,β-不饱和硫代酰胺的详细研究。一种柔软的路易斯酸/硬布朗斯台德碱协同催化剂,包含[Cu(CH 3 CN)4 ] PF 6,双膦配体和Li(OC 6 H 4 - p‐OMe)同时激活两种底物以补偿炔烃铜的低反应性。一系列控制实验表明,中间体铜硫代酰胺醇烯酸酯起布朗斯台德碱的作用,从末端炔烃生成炔烃铜,从而通过底物之间的有效质子转移驱动催化循环。这些发现导致鉴定了使用六甲基二硅氮烷钾(KHMDS)作为布朗斯台德碱的更方便的催化剂,该催化剂对于甲硅烷基乙炔的反应特别有效。硫酰胺官能团的不同转化以及GPR40受体激动剂AMG-837的简洁对映选择性合成突出了本催化方法的合成用途。