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Updated: Apr 5, 2026

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
A DFT Study on the Mechanism of Selective Formation of Substituted Azepines From 1-Azabutadienes and Cyclopropanes
Ryo Kobayashi1, Chao Wang1, Shuto Kosuge2
1Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan.
Abstract:
Density Functional Theory (DFT) calculations were performed to elucidate the reaction mechanism of the Mg-catalyzed cyclization between an azadiene-type imine and a cyclopropane. The results reveal that the [4+3] cyclization pathway leading to azepine formation is both kinetically and thermodynamically preferred over the intuitively more accessible [3+2] pathway toward pyrrolidine formation. This unusual selectivity arises from the interplay of opposing electronic and steric effects, with steric effects ultimately dominating.
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