Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, 610064, China.
Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China.
Angew Chem Int Ed Engl. 2017 Oct 9;56(42):13107-13111. doi: 10.1002/anie.201705943. Epub 2017 Sep 8.
The first enantioselective conjugate addition of silyl ketene imines to in situ generated indol-2-ones was performed in the presence of a chiral N,N'-dioxide/Ni catalyst. This method provides efficient access to chiral β-alkyl nitriles bearing congested vicinal all-carbon quaternary stereocenters in up to 90 % yield with 23:1 d.r. and 98 % ee. The products enable facile transformations to chiral pyrroloindoline frameworks and spirocyclohexane oxindole derivatives. A possible transition state was also proposed to explain the origin of the asymmetric induction.
手性 N,N'-二氧化物/镍催化剂存在下，首次实现了硅烯酮亚胺与原位生成的吲哚-2-酮的对映选择性共轭加成。该方法以高达 90%的收率、23:1 的 dr 和 98%的 ee 值，高效构建了手性β-烷基腈，其中包含拥挤的偕二碳季碳立体中心。产物可方便转化为手性吡咯并吲哚啉骨架和螺环环己烷氧化吲哚衍生物。还提出了一种可能的过渡态，以解释不对称诱导的起源。
