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Updated: Jun 27, 2026
11:45
Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Exploring synthetic routes to 6-functionalized 4-azaspiro[2.3]hexanes
Wei Huang1, Kangqiao Wen1, Scott T Laughlin1
1Department of Chemistry, Stony Brook University, USA. scott.laughlin@stonybrook.edu.
Organic & Biomolecular Chemistry
|June 26, 2026
Summary
This study introduces a new method for synthesizing 6-functionalized 4-azaspiro[2.3]hexanes, important for medicinal chemistry. The optimized synthesis uses readily available azetidines and avoids hazardous catalysts, yielding valuable piperidine bioisostere analogues.
Area of Science:
- Medicinal Chemistry
- Organic Synthesis
- Chemical Biology
Background:
- Azaspirohexanes are valuable scaffolds for creating piperidine bioisosteres.
- Previous research concentrated on 5-azaspiro[2.3]hexane analogues.
- The synthesis of 6-functionalized 4-azaspiro[2.3]hexanes was largely unexplored.
Purpose of the Study:
- To develop a synthetic route for 6-functionalized 4-azaspiro[2.3]hexane analogues.
- To explore the utility of substituted azetidines as key intermediates.
- To establish efficient and safe synthetic methodologies.
Main Methods:
- Utilized substituted azetidines (fluoro-, dimethoxy-, methoxybenzyl-) as intermediates.
- Optimized intramolecular ring closure of an acyclic amine for azetidine synthesis.
- Employed azetidine enamine intermediates for spirocycle formation.
Main Results:
- Achieved efficient synthesis of 3,3-dimethoxy-2-ester azetidine via intramolecular ring closure.
- Successfully synthesized two 6-functionalized 4-azaspiro[2.3]hexanes: 6-OBn-4-azaspiro[2.3]hexane and 6-dimethoxy-4-azaspiro[2.3]hexane.
- The developed method avoids hazardous materials and precious-metal catalysts.
Conclusions:
- Established a viable synthetic pathway for 6-functionalized 4-azaspiro[2.3]hexanes.
- The synthesized compounds represent novel motifs for medicinal chemistry and chemical biology.
- The method offers a safe and efficient alternative for accessing these important scaffolds.
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In cyclohexane, the substituents can occupy different positions generating distinct isomers.
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
01:16Structure of Conjugated Dienes
Introduction
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