- Palladium-Catalyzed Aerobic Oxidative Carbonylation of Amines Enables the Synthesis of Unsymmetrical N,N′-Disubstituted Ureas
-
A ligand-free palladium-catalyzed aerobic oxidative carbonylation of amines for the synthesis of ureas, particular unsymmetrically N,N′-disubstituted ureas, which cannot be accessed by any other palladium-catalyzed oxidative carbonylation of amines to date, is presented. An array of symmetrical and unsymmetrical ureas were straightforwardly synthesized by using inexpensive, readily available, stable, and safe amines with good to excellent yields under a pressure of 1 atm. This novel method employs oxygen as the sole oxidant and offers an attractive alternative to transition-metal-based oxidant systems.
- Zeng, Honglan,Du, Hongyan,Gong, Xu,Zhang, Jie,Han, Wei
-
p. 1223 - 1226
(2021/06/02)
-
- Method for catalytically synthesizing N, N'-disubstituted urea derivative and imidazole derivative
-
The present invention relates to a green and efficient method for preparing an N, N'-disubstituted urea derivative and an imidazole derivative. The method for preparing the N, N'-disubstituted urea derivative by condensation of an aromatic amine with a carbonate ester comprises: by using ionic liquid loaded magnetic nanoparticles as a catalyst, at the temperature of 60-100 DEG C, and at a normal pressure, and in a condition of solvent-free, performing a condensing reaction on the aromatic amine and the carbonate ester for 8-14 hours to obtaina corresponding N, N'-disubstituted urea derivative; by using a magnetic nanoparticle-loaded ionic liquid as a catalyst and by using ethanol as a solvent, performing Michael addition reaction of a substituted imidazole and an electron-deficient olefin for 1-5 hours at the temperature of 10-50 DEG C and at a normal pressure to obtain a corresponding imidazole derivative, wherein the catalyst is as shown in the specification. Experiments verify that after the reaction is completed, the catalyst is recycled simply through an external magnetic field and can be repeatedly used for many times, but the activity is not obviously reduced. The catalytic system is simple in operation and high in yield, and the reusability is good, so that the method has a good industrial prospect.
- -
-
Paragraph 0052; 0053; 0054; 0055
(2016/10/17)
-
- 153. Azimine. VII. Herstellung durch Oxydation von Triazanen
-
A novel method for the preparation of certain azimines 4 by oxidation of 1,2,3-trisubstituted triazanes 3 is described.Treatment of 3-aryl-triazane-1,2-diesters 3a-3c with lead tetraacetate afforded the 3-aryl-azimine-1,2-diesters 4a-4c.The precursor tria
- Egger, Notker,Hoesch, Lienhard,Dreiding, Andre S.
-
p. 1599 - 1607
(2007/10/02)
-