Related Experiment Video
Updated: May 9, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Determination of the Absolute Configuration by 3D ED to Elucidate the Atroposelectivity in Aromatic Ring-Opening
Valeriia Hutskalova1, Christian Jandl2, Alessandro Prescimone3
1Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland. valeriia.hutskalova@unibas.ch.
Abstract:
The determination of the absolute configuration of molecules bearing different stereogenic elements represents a fundamental and indispensable task in the field of stereochemistry. Whereas X-ray crystallographic analysis has been established as a broadly utilized and reliable technique to achieve this goal, limitations remain arising from the demanding requirements for the size and diffraction quality of the analyzed crystals. As an emerging technique, 3D microcrystal electron diffraction (3D ED) has increasingly been recognized to complement single crystal X-ray diffraction (SC-XRD). Having encountered challenges in determining the absolute configuration for the products obtained during the development of atroposelective aromatic ring-opening metathesis (AArROM), we herein describe in detail, how 3D ED allowed an assignment, which proved unfeasible using the conventional approach with X-ray crystallography.
More Related Videos
Related Concept Videos
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Nucleophilic Aromatic Substitution: Addition–Elimination (SNAr)
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between...
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

