Dearomative [4 + 2] cycloaddition of 3‐nitroindoles with <i>ortho</i>‐amino <scp>Morita−Baylis−Hillman</scp> carbonates to forge indole‐fused quinolines
Kai‐Kai Wang, Yanli Li, Lanxin Li, Weiwei Yao, Ya‐Fei Li, Wen‐Fei Wang, Rongxiang Chen, Y. Hu, Aili Sun
Abstract
Abstract A dearomative [4 + 2] cycloaddition of 3‐nitroindoles ortho ‐amino Morita−Baylis−Hillman carbonates was established under mild conditions. This method provides an efficient and practical approach for delivering tetrahydro‐5 H ‐indolo[2,3‐ b ]quinolines containing three contiguous stereocenters, two tertiary and one quaternary, in high yield (up to 95%) with excellent diastereoselectivity (all cases >25:1 dr ). The potential synthetic applications of this strategy were also highlighted by the scale‐up experiment and further synthetic transformation. Moreover, the structure and relative configuration of the cycloadduct was unequivocally confirmed by single‐crystal X‐ray diffraction.