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Updated: Dec 28, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Synthesis and Conformational Analysis of Parent Perhydroazulenes Reveal an Energetically Preferred cis Ring Fusion
Fumito Saito1, Jonathan Becker2, Peter R Schreiner1
1Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.
Abstract:
Perhydroazulenes are common structural motifs in various terpene natural products. Herein, we present the synthesis of parent cis- and trans-perhydroazulenes. Conformational analysis performed with density functional theory (DFT, e.g., B3LYP, M06-2X) and MP2 geometry optimizations with a cc-pVTZ basis set, followed by CCSD(T)/cc-pVTZ single-point energy computations reveals that the cis isomer is 0.7 kcal mol-1 more stable than the trans isomer. Steric and torsional strains present in the trans isomer are responsible for this unexpected relative cis/trans stability.
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