Related Experiment Video
Updated: Apr 27, 2026

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Antiaromaticity to aromaticity: from boroles to 1,2-azaborinines by ring expansion with azides
Holger Braunschweig1, Christian Hörl, Lisa Mailänder
1Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany) http://www-anorganik.ak-braunschweig.chemie.uni-wuerzburg.de/. h.braunschweig@uni-wuerzburg.de.
Abstract:
We have exploited the reactivity of antiaromatic boroles, gaining access to aryl-substituted monocyclic 1,2-azaborinines. The observed ring-expansion reaction of inherently electron-deficient boroles with organometallic and organic azides is demonstrated for representative examples. This substance class is expected to provide a new avenue into 1,2-azaborinine chemistry, especially in the area of functional organoboron materials. Our results are based on NMR and UV/Vis spectroscopy as well as single-crystal X-ray crystallography and provide a virtually quantitative approach that also offers numerous points of variation.
Related Concept Videos
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Nucleophilic Aromatic Substitution: Elimination–Addition
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
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...

