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Carbonyldiimidazole-Mediated Lossen Rearrangement

Pascal Dubé*, Noah F. Fine Nathel, Michael Vetelino, Michel Couturier, Claude Larrive Aboussafy, Simon Pichette, Matthew L. Jorgensen and Mark Hardink

*Chemical Research and Development, Pfizer Global Research and Development, Eastern Point Road, P.O. Box 8013, Groton, Connecticut 06340-8013, Email:

P. Dubé, N. F. F. Nathel, M. Vetelino, M. Couturier, C. L. Abossafy, S. Pichette, M. L. Jorgensen, M. Hardink, Org. Lett., 2009, 11, 5622-5625.

DOI: 10.1021/ol9023387


Carbonyldiimidazole mediates the Lossen rearrangement of various hydroxamic acids to isocyanates. This process is experimentally simple and mild, with imidazole and CO2 being the sole stoichiometric byproduct. The method avoids the use of hazardous reagents and thus represents a green alternative to standard processing conditions for the Curtius and Hofmann rearrangements.

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proposed reaction pathway

Key Words

Lossen Rearrangement, Urea Derivatives, Carbamates, Hydroxamic Acids

ID: J54-Y2009-3660