An unusual radical Smiles rearrangement
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Updated: Aug 16, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Eric Bacqué1, Myriem El Qacemi, Samir Z Zard
1Laboratoire de Synthèse Organique associé au CNRS, Ecole Polytechnique, 91128 Palaiseau, France.
Abstract:
Radicals derived from N-(alpha-xanthyl)acetanilides or N-(alpha-xanthyl)acetylaminopyridines possessing a substituent next to the nitrogen undergo a hitherto undocumented Smiles rearrangement proceeding through a four-membered ring. It was also found that under certain conditions the amidyl radical produced by cleavage of the four-membered ring intermediate can undergo fragmentation to give an isocyanate. Such fragmentations are unprecedented at temperatures corresponding to refluxing benzene or chlorobenzene. [reaction: see text]
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