Unprecedented “In Water” Imidazole Carbonylation: Paradigm Shift for Preparation of Urea and Carbamate
摘要:
The first "In Water" Imidazolecarbonylation of amine is described. A one pot reaction of carbonylimidazolide in water with a nucleophile provides an efficient and general method for the preparation of urea, carbamates and thiocarbamates. Use of an anhydrous solvent and an inert atmosphere could be avoided. Product precipitate out from the reaction mixture and can be obtained In high purity by filtration, resulting in a simple and scalable method.
Synthesis of ureas in the bio-alternative solvent Cyrene
作者:Liam Mistry、Kopano Mapesa、Thomas W. Bousfield、Jason E. Camp
DOI:10.1039/c7gc00908a
日期:——
Cyrene as a bio-alternative solvent: a highly efficient, waste minimizing protocol for the synthesis of ureas from isocyanates and secondary amines in the bio-available solvent Cyrene is reported. This method eliminated the use of toxic solvents, such as DMF, and established a simple work-up procedure for removal of the Cyrene, which led to a 28-fold increase in molar efficiency versus industrial standard
(TFE) promoted synthesis of unsymmetric ureas was described. This approach enabled the construction of a variety of ureas from the readily prepared and easy-to-handle dioxazolones and amines viatandem Lossen rearrangement/condensation process. The reaction featured mild conditions for the urea synthesis under metal-free conditions, which was successively applied in the scale-up synthesis of herbicides
Metal-Free Oxidative C-H Amidation of<i>N</i>,<i>N′</i>-Diarylureas with PhI(OAc)<sub>2</sub>: Synthesis of Benzimidazol-2-one Derivatives
作者:Jipan Yu、Chang Gao、Zhixuan Song、Haijun Yang、Hua Fu
DOI:10.1002/ejoc.201500726
日期:2015.9
compounds or intramolecular N-arylations using substrates with carbon-halogen bonds. However, the starting materials of these protocols are often not readily available. Herein, a simple and practical metal-free oxidative C–H amidation of N,N′-diarylureas has been developed that takes place at room temperature. This protocol uses readily available N,N′-diarylureas as the starting materials and inexpensive