1-Propanephosphonic Acid Cyclic Anhydride (T3P) as an Efficient Promoter for the Lossen Rearrangement: Application to the Synthesis of Urea and Carbamate Derivatives
The synthesis of hydroxamic acids starting from carboxylic acids employing 1-propanephosphonic acid cyclic anhydride (T3P) activation is described. Application of ultrasonication accelerates this conversion. Further, the T3P has also been employed to activate the hydroxamates, leading to isocyanates via the Lossenrearrangement. The isocyanates were trapped with suitable nucleophiles to afford the
New and simple synthesis of acid azides, ureas and carbamates from carboxylic acids: application of peptide coupling agents EDC and HBTU
作者:Vommina V. Sureshbabu、H. S. Lalithamba、N. Narendra、H. P. Hemantha
DOI:10.1039/b920290k
日期:——
Conversion of carboxylic acids into acid azides using peptide coupling agents, EDC and HBTU is described. The procedure is efficient, practical and applicable to a diverse range of carboxylic acids including N-protected amino acids. Using the same reagents, one-pot synthesis of ureas, dipeptidyl urea esters and carbamates from acids has also been achieved.
Efficient Direct Halogenation of Unsymmetrical N-Benzyl- and N-Phenylureas with Trihaloisocyanuric Acids
作者:Lúcia de Aguiar、Marcio de Mattos、Carlos Sanabria、Bruno Costa、Gil Viana
DOI:10.1055/s-0036-1589149
日期:2018.3
halogenation of N-phenylureas was developed using trihaloisocyanuric acids in acetonitrile at room temperature. This protocol proved to be effective for the construction of N-phenylureas with different patterns of substitution. Additionally, less reactive N-benzylureas were halogenated in the presence of a mixture of trifluoroacetic acid and acetonitrile at room temperature. A simple and efficient methodology