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Cascade Dearomative Hydride Transfer/Enantioselective Semipinacol Rearrangement of Quinolines by a Chiral Brønsted
Xuan Yu1,2, Hui Xu1, Chao Zheng1
1New Cornerstone Science Laboratory, State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
Abstract:
Herein, we report a chiral Brønsted-acid-catalyzed dearomatization of quinolines. The reaction proceeds via dearomative hydride transfer and subsequent enantioselective semipinacol rearrangement. The key to this reaction sequence is to guide the imine intermediate to a rearrangement pathway other than over-reduction. Utilizing a bulky chiral imidodiphosphorimidate catalyst guarantees the desired reactivity. A series of chiral spiro tetrahydroquinoline products is afforded in good yields (up to 93%) and enantioselectivity (up to 93% ee). Detailed mechanistic insights are obtained based on DFT calculations.
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