Urea Anions: Simple, Fast, and Selective Catalysts for Ring-Opening Polymerizations
作者:Binhong Lin、Robert M. Waymouth
DOI:10.1021/jacs.6b11864
日期:2017.2.1
the reactivities of several diaryl urea anions correlated to the electron-withdrawing substituents on the aryl rings. With the appropriate urea anions, the polymerizations reached high conversions (∼90%) at room temperature within seconds (1-12 s), yielding polymers with narrow molecular weight distributions (Đ = 1.06 to 1.14). These versatile catalysts are simple to prepare, easy to use, and exhibit
Amines and substituted ureas are produced by reaction of carboxamides with hypochlorites in the presence of bromine, iodine, polymerization inhibitors, and/or haloamides and excess alkali metal hydroxide with or without the addition of primary or secondary amines. The products are perfumes and starting materials for the production of dyes, plant protection agents and perfumes.
Assembly of N,N-disubstituted-N′-arylureas via a copper-catalyzed one-pot three-component reaction of aryl bromides, potassium cyanate, and secondary amines
作者:Hongfei Yin、Bing Chen、Xiaojing Zhang、Xinye Yang、Yihua Zhang、Yongwen Jiang、Dawei Ma
DOI:10.1016/j.tet.2013.04.117
日期:2013.7
A three-component reaction of aryl bromides, potassiumcyanate, and secondary amines takes place at 110 °C in MeCN under the catalysis of Cu2O and 2-(2,6-dimethylphenylamino)-2-oxoacetic acid potassium salt, giving N,N-disubstituted-N′-arylureas in good to excellent yields. A number of functionalized aryl bromides and secondary amines were compatible with these conditions, and thereby providing a facile
(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
Palladium-Catalyzed Synthesis of Symmetrical and Unsymmetrical Ureas Using Chromium Hexacarbonyl as a Convenient and Safe Alternative Carbonyl Source
作者:Mozhdeh Mozaffari、Najmeh Nowrouzi
DOI:10.1002/ejoc.201901273
日期:2019.12.15
Different symmetrical and unsymmetrical ureas can be synthesized through a Pd‐catalyzed carbonylation of aryl iodides using chromium hexacarbonyl. Curtius rearrangement occurs in the presence of sodium azide which is followed by nucleophilicaddition of different amines to afford the products in good to excellent yields.