The synthesis of N-substituted ureas II: Nucleophilic substitution of ureas at the carbonyl group
作者:Kurt A. Hackl、Heinz Falk
DOI:10.1007/bf00816856
日期:——
N-Arylsubstituted ureas undergo exchange of the N'-residue upon reaction with amines. Using kinetic measurements, investigation of product distribution, regioselectivity, catalysis, and substrate influences, it was shown that this reaction proceeds via a second order nucleophilic substitution at the urea carbonyl center. By means of semiempirical calculations using the MNDO method the alternative mechanism of fragmentation was investigated.
US5283362A
申请人:——
公开号:US5283362A
公开(公告)日:1994-02-01
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