α-Haloalkyl Haloformates and Related Compounds 3.<sup>1</sup>A Facile Synthesis of Symmetrical and Unsymmetrical Ureas<i>via</i>Chloromethyl Carbamates
Abstract Chloromethyl carbamates were prepared by the reaction of chloromethyl chloroformates with amines and found to produce mono-, symmetrically or unsymmetrically di-and trisubstituted ureas including their N-hydroxy and N-alkoxy derivatives in moderate to good yield.
CaI<sub>2</sub>-Catalyzed direct transformation of <i>N</i>-Alloc-, <i>N</i>-Troc-, and <i>N</i>-Cbz-protected amines to asymmetrical ureas
作者:Van Hieu Tran、Hee-Kwon Kim
DOI:10.1039/c9nj03111a
日期:——
CaI2-catalyzed direct synthesis of asymmetrical ureas from N-Alloc-, N-Troc-, and N-Cbz-protected amines is developed. In this study, the efficient reaction of Alloc-, Troc-, and Cbz-carbamates with amines in the presence of catalytic CaI2 successfully generated various asymmetrical ureas. This catalytic synthetic procedure provided the desired ureas via reactions of these protected aromatic and aliphatic
Oximes as reusable templates for the synthesis of ureas and carbamates by an in situ generation of carbamoyl oximes
作者:Gopal Chandru Senadi、Mohana Reddy Mutra、Ting-Yi Lu、Jeh-Jeng Wang
DOI:10.1039/c7gc01449j
日期:——
Oximes have been identified as a reusable template for the synthesis of ureas and carbamates by an in situ generation of carbamoyl oximes under metal-free conditions. The recycled oxime has been carried out for three trials in the synthesis of urea derivatives without any loss in the yield and efficiency. In addition, this template approach could override the usage of hazardous and less stable isocyanates
Visible-light-promoted oxidative desulphurisation: a strategy for the preparation of unsymmetrical ureas from isothiocyanates and amines using molecular oxygen
作者:Ziyu Gan、Guoqing Li、Qiuli Yan、Weiseng Deng、Yuan-Ye Jiang、Daoshan Yang
DOI:10.1039/d0gc00070a
日期:——
A green and efficient visible-light promoted oxidative desulphurisation protocol has been proposed for the construction of unsymmetrical ureas under mild conditions with broad substrate scope and good functional group tolerance. Most appealingly, the reaction can proceed smoothly without adding any strong oxidants. Control experiments and computational studies support a mechanism involving water-assisted
Scalable, One-Pot, Microwave-Accelerated Tandem Synthesis of Unsymmetrical Urea Derivatives
作者:Abhijit R. Kulkarni、Sumanta Garai、Ganesh A. Thakur
DOI:10.1021/acs.joc.6b02521
日期:2017.1.20
We report a facile, microwave-accelerated, one-pottandemsynthesis of unsymmetrical ureas via a Curtius rearrangement. In this method, one-pot microwave irradiation of commercially available (hetero)aromatic acids and amines in the presence of diphenylphosphoryl azide enabled extremely rapid (1–5 min) construction of an array of unsymmetrical ureas in good to excellent yields. We demonstrate the utility