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Updated: Oct 1, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
(3 + 2) Cycloaddition Reaction of the Endocyclic N-Silyl Enamine and N,N'-Cyclic Azomethine Imine
Vinh Do Cao1, Huiae Kim1, Jaesung Kwak2
1Department of Chemistry, Mokpo National University, Muan, Jeonnam 58554, Republic of Korea.
Abstract:
We describe the (3 + 2) cycloaddition reaction of endocyclic N-silyl enamines and N,N'-cyclic azomethine imines. This process utilized the versatile endocyclic N-silyl enamine intermediates from the dearomative hydrosilylation of N-heteroarenes. The resulting tetracyclic pyrazolidinone structure was synthesized by a straightforward and atom-economical process. We also discussed the plausible origins of the different reactivity and endo/exo selectivity in terms of the structures of each proposed transition state. The successful gram-scale synthesis demonstrated the synthetic utility.
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