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Updated: Sep 30, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Rhodium-Catalyzed Ring Expansion of Azetidines via Domino Conjugate Addition/N-Directed α-C(sp3)-H Activation
Ling-Zhi Sun1, Xuan Yang1, Nan-Nan Li1
1Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling 712100, China.
Abstract:
A facile synthetic method for 4-aryl-4,5-dihydropyrrole-3-carboxylates is developed, with a rhodium-catalyzed ring expansion strategy from readily available 2-(azetidin-3-ylidene) acetates and aryl boronic acids. Mechanistic investigations suggest a novel domino "conjugate addition/N-directed α-C(sp3)-H activation" process. The asymmetric catalytic synthesis of the 4-aryl-4,5-dihydropyrrole-3-carboxylate is realized by using QuinoxP* (91-97% ee). The synthetic utility of this protocol is demonstrated by the synthesis of 3,4-disubstituted or 2,3,4-trisubstituted pyrrolidines with excellent diastereoselectivities.
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