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Squaramide‐Catalyzed Synthesis of Enantioenriched Spirocyclic Oxindoles via Ketimine Intermediates with Multiple Active Sites |
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| Authors: | Qiang‐Sheng Sun Hua Zhu Yong‐Jian Chen Dr. Xiao‐Di Yang Prof. Xing‐Wen Sun Prof. Guo‐Qiang Lin |
| Affiliation: | 1. Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China);2. Shanghai Institute of Organic Chemistry, CAS, 354 Fenglin Road, Shanghai, 200032 (China) |
| Abstract: | A new method for the construction of five‐membered spirocyclic oxindoles is based on a Michael–Mannich cascade reaction of a ketimine intermediated catalyzed by a bifunctional quinine‐derived squaramide. The desired products were obtained in excellent yields (up to 94 %) and stereoselectivities (up to >20:1 d.r., >99 % ee). A scaled‐up variant also proceeded smoothly showing that the one‐pot reaction might find application in the synthesis of bioactive‐compound libraries. |
| Keywords: | asymmetric synthesis ketimines Mannich reactions Michael additions nitrogen heterocycles organocatalysis |