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Asymmetric [3 + 2] Cycloaddition of 3‑Amino Oxindole-Based Azomethine Ylides and α,β-Enones with Divergent Diastereocontrol on the Spiro[pyrrolidine-oxindoles]

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journal contribution
posted on 27.03.2017, 20:31 by Guodong Zhu, Qian Wei, Hongbo Chen, Yanpeng Zhang, Wen Shen, Jingping Qu, Baomin Wang
A general and practical organocatalytic asymmetric 1,3-dipolar cycloaddition of 3-amino oxindole-based azomethine ylides and α,β-enones has been developed. This reaction delivered spiro­[pyrrolidine-2,3′-oxindole] products in high yields with excellent regio- and enantioselectivities (up to 99% yield, >20:1 rr, 99% ee). In addition, an array of spiro­[dihydropyrrole-2,3′-oxindoles] were readily accessed by oxidative dehydrogenation. Notably, the inversion of the diastereoselectivity of the spiro­[pyrrolidine-oxindole] product could be easily achieved through a facile oxidation–reduction process.