A sensitive amine-responsive disassembly of self-assembled AuI -CuI double salts was observed and its utilization for the synergistic catalysis was enlightened. Investigation of the disassembly of [Au(NHC)2 ][CuI2 ] revealed the contribution of Cu-assisted ligand exchange of N-heterocyclic carbene (NHC) by amine in [Au(NHC)2 ]+ and the capacity of [CuI2 ]- on the oxidative step. By integrating the
phenethylamine derivatives, underwent a direct aromatic carbonylation to afford five- or six-membered benzolactams. In the carbonylation, the chelation effect or steric repulsion between Pd(II) and the meta-substituent in the ortho-palladation and the ring sizes of cyclopalladation products that were formed prior to carbonylation were found to generate good site selectivity and increase the reaction rate. In
observed in situ, which resulted in the formation of CO and dimethylamine. The scope of this new mode of bond activation is extended to the synthesis of urea derivatives from amines using DMF as a carbon monoxide (CO) surrogate. This catalytic protocol allows the synthesis of simple and functionalized urea derivatives with liberation of hydrogen, devoid of any stoichiometric activating reagents, and avoids
Palladium-mediated oxidative carbonylation reactions for the synthesis of<sup>11</sup>C-radiolabelled ureas
作者:Steven Kealey、Stephen M. Husbands、Idriss Bennacef、Antony D. Gee、Jan Passchier
DOI:10.1002/jlcr.3151
日期:2014.4
Palladium(II)-mediated oxidative carbonylation reactions have been used to synthesize 11C-radiolabelled ureas via the coupling of amines with [11C]carbon monoxide, in a one-pot process. Following trapping of 11CO in a solution of copper(I) tris(3,5-dimethylpyrazolyl)borate, homocoupling reactions of primary aliphatic amines proceed in the presence of Pd(PPh3)2Cl2 to give the corresponding N,N-disubstituted [11C]ureas. Secondary amines do not produce the corresponding N,N,N,N-tetrasubsituted [11C]ureas under these conditions. This difference in reactivity allows for the formation of unsymmetrical N,N’,N’-trisubstituted [11C]ureas using a mixture of a primary amine and a reactive secondary amine. The potential use of this method in positron emission tomography (PET) was demonstrated by the synthesis of the M1 muscarinic acetylcholine receptor radiotracer, [11C-carbonyl]GSK1034702.
A convenient synthesis of symmetrical N,N′-dialkylureas by the reactions of 4-chloro-5H-1,2,3-dithiazol-5-one with alkylamines
作者:Yong-Goo Chang、Hyi-Seung Lee、Kyongtae Kim
DOI:10.1016/s0040-4039(01)01761-0
日期:2001.11
Treatment of 4-chloro-5H-1,2,3-dithiazol-5-one with primary and secondary alkylamines (>2 equiv.) in CH2Cl2 at rt afforded symmetrical N,N′-disubstituted ureas in moderate to good yields. Similarly, the reactions with amino acid ester hydrochlorides in the presence of Et3N (>3 equiv.) under the same conditions gave symmetrical ureas.
在室温下,在CH 2 Cl 2中用伯和仲烷基胺(> 2当量)处理4-氯-5 H -1,2,3-二噻唑-5-酮,得到对称的N,N'-二取代脲良品率高。类似地,在相同条件下,在Et 3 N(> 3当量)存在下,与氨基酸盐酸盐的反应生成对称的脲。