Asymmetric triple relay catalysis: enantioselective synthesis of spirocyclic indolines through a one-pot process
Xiao-Ping Yin1, Xing-Ping Zeng, Yun-Lin Liu
1Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663N, Zhongshan Road, Shanghai 200062 (China).
Abstract:
A rare example of a one-pot process that involves asymmetric triple relay catalysis is reported. The key step is an asymmetric [1,5] electrocyclic reaction of functionalized ketimines. The substrates for this process were obtained in situ in a two-step process that involved the hydrogenation of nitroarenes with a Pd/C catalyst to yield aryl amines and their subsequent coupling with isatin derivatives in a Brønsted acid catalyzed ketimine formation reaction. The electrocyclization was catalyzed by a bifunctional chiral Brønsted base/hydrogen bond donor catalyst. The one-pot process gave the desired products in good yields and with excellent enantioselectivity.
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