Department of Chemistry , Indian Institute of Technology Madras , Chennai - 600036 , Tamil Nadu , India.
Org Lett. 2019 Feb 15;21(4):867-871. doi: 10.1021/acs.orglett.8b03557. Epub 2019 Jan 29.
A Cu(II)-catalyzed domino process involving the carbene N-H insertion, intramolecular aldol-type trapping and unprecedented ring-expansion of oxindole core through C3-selective 1,2-carbonyl migration is described for the synthesis of indolo[3,2- c]quinolinones. This tetracyclic core, having an all-carbon quaternary center, was efficiently synthesized in high yields from amines and 3-diazo-oxindoles. Mechanistic studies revealed that this reaction proceeds via a stepwise pathway and the involvement of the synergistic catalysis between Lewis acidic copper and hidden Brønsted acidity of in-situ-formed TfOH traces.
一种铜（II）催化的串联过程，涉及卡宾 N-H 插入、分子内醛醇型捕获以及通过 C3-选择性 1,2-羰基迁移对色酮核心的前所未有的环扩张，用于吲哚并[3,2-c]喹啉酮的合成。这种四环核心，具有全碳季碳原子，能够高效地从胺和 3-重氮色酮出发，以高产率合成。机理研究表明，该反应通过分步途径进行，路易斯酸性铜和原位形成的 TfOH 痕迹的隐藏 Brønsted 酸性之间的协同催化作用。
