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Updated: Jun 29, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Carbene-alkene complexes between a nucleophilic carbene and electron-poor alkenes
Jean-Luc Mieusset1, Michael Abraham, Udo H Brinker
1Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Austria.
Abstract:
Spirooxadiazoline 5 is a clean thermal source of tricyclo[6.2.1.0 (2,7)]undec-9-en-11-ylidene (7), a typical foiled carbene. Species 7 can be trapped efficiently at 165 degrees C by electron-deficient alkenes like acrylonitrile and fumaronitrile whereby the anti addition products are obtained exclusively. Higher temperatures, however, favor intramolecular reactions. Density functional theory (DFT) calculations predict the formation of a strong complex between both reactants which actually is a minimum on the free energy scale. These results confirm the nucleophilic character of foiled carbenes and the presence of a significant barrier toward rearrangement.
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