A Pd/C‐catalyzed domino synthesis of symmetrical and unsymmetrical ureas fromaryl iodides, sodium azide, amines and CHCl3 in water has been developed. This reaction proceeds with sequential carbonylation, Curtius rearrangement and nucleophilic addition. CHCl3 serves as a convenient and safe alternation of CO gas in the presence of KOH. A series of urea derivatives were obtained in moderate to good
Microwave Assisted, Solvent- and Ligand-Free Copper Catalyzed N-Arylation of Phenylurea with Aryl Halides
作者:Sandip Gavade、Murlidhar Shingare、Dhananjay Mane
DOI:10.5012/bkcs.2011.32.12.4167
日期:2011.12.20
An inexpensive and efficient catalyst system has been developed for the N-arylation of phenylurea including a variety of aryl halides. This simple protocol uses $Cu_2O$ as the catalyst, microwave assisted, solvent- and ligand-free, $K_3PO_4\cdot}H_2O$ as the base.
Abstract A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in refluxing dioxane and does not require any catalyst or additives.
Unsymmetrical ureas and S-thiocarbamates were prepared in good to excellent yields by direct condensation of phenylurea with amines and thiols in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) without the addition of any additives. The [BMIM]BF4 ionic liquid is a mild medium and can be recycled and reused several times.