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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Practical synthesis of unsymmetrical ureas from isopropenyl carbamates
Isabelle Gallou1, Magnus Eriksson, Xingzhong Zeng
1Department of Chemical Development, Boehringer Ingelheim Pharmaceutical, Inc., 900 Ridgebury Road, Ridgefield, CT 06877, USA. igallou@rdg.boehringer-ingelheim.com
Abstract:
A very convenient method for the synthesis of unsymmetrical ureas is described, based on isopropenyl carbamates. The synthetic efficiency of traditional methods for urea formation, such as use of phosgene or alkyl and aryl carbamates, is limited by the formation of symmetrical urea side products or reaction reversibility. Isopropenyl carbamates react with amines cleanly and irreversibly and give unsymmetrical ureas in high yield and purity. This method is ideal for the rapid synthesis of compound libraries.
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