Reactivity of Carbamoyl Radicals. A New, General, Convenient Free-Radical Synthesis of Isocyanates from Monoamides of Oxalic Acid
摘要:
A new, general, simple synthesis of isocyanates was developed by oxidation of monoamides of oxalic acid with peroxydisulfate catalyzed by Ag and Cu salts. The reaction was carried out in a two-phase system (water and an organic solvent), and it is suitable also for practical applications, due to the simple experimental conditions and the inexpensive as well as nontoxic reagents. The first example of homolytic intramolecular aromatic carbamoylation is also reported.
CuI/Oxalic Diamide-Catalyzed Cross-Coupling of Thiols with Aryl Bromides and Chlorides
作者:Chia-Wei Chen、Yi-Ling Chen、Daggula Mallikarjuna Reddy、Kai Du、Chao-En Li、Bo-Hao Shih、Yung-Jing Xue、Chin-Fa Lee
DOI:10.1002/chem.201701671
日期:2017.7.26
We report a general copper‐catalyzed cross‐coupling of thiols with arylhalides by using N‐aryl‐N′‐alkyl oxalic diamide (L3) or N,N′‐dialkyl oxalic diamide (L5) as the ligand. Both aryl and alkyl thiols can be coupled with unactivated aryl bromides and chlorides to give the desired products in good yields. Furthermore, this system features a broad substrate scope and good tolerance of functional groups
我们通过使用报告与芳基卤硫醇的一般铜-催化的交叉偶联ñ -芳基- N' -烷基草酸二酰胺(L3)或ñ,N' -二烷基二酰胺草酸(L5)作为配体。芳基和烷基硫醇都可以与未活化的芳基溴化物和氯化物偶合,以高收率得到所需的产物。此外,该系统具有广泛的底物范围和对官能团的良好耐受性。重要的是,草酸二酰胺是稳定的,并且可以容易地由市售和廉价的起始原料制备。
A Novel PdCl2/ZrO2–SO2−4 Catalyst for Synthesis of Carbamates by Oxidative Carbonylation of Amines
作者:Feng Shi、Youquan Deng、Tianlong SiMa、Hongzhou Yang
DOI:10.1006/jcat.2001.3350
日期:2001.10
At 170°C and ca. 4.0 MPa, oxidative carbonylation of aromatic amines to synthesize corresponding carbamates over a novel PdCl2/ZrO2–SO2−4 catalyst could proceed with high conversion and selectivity.
Oxamides were obtained in moderate to good yields by the reaction of isocyanates with the SmI2/HMPA/THF system under mild conditions. The system also caused desulfurization of isothiocyanates to give isocyanides in good yields.
A sustainable, new synthesis of oxalamides, by acceptorless dehydrogenativecoupling of ethylene glycol with amines, generating H2, homogeneously catalyzed by a rutheniumpincercomplex, is presented. The reverse hydrogenation reaction is also accomplished using the same catalyst. A plausible reaction mechanism is proposed based on stoichiometric reactions, NMR studies, X-ray crystallography as well
A novel ZrO2–SO42− supported palladium catalyst for syntheses of disubstituted ureas from amines by oxidative carbonylation
作者:Feng Shi、Youquan Deng、Tianlong SiMa、Hongzhou Yang
DOI:10.1016/s0040-4039(01)00124-1
日期:2001.3
The syntheses of disubstituted ureas by carbonylation of a series of amines in the presence of a sulfate modified zirconia supported palladium catalyst was investigated at an initial total pressure of 4.0 MPa and 135°C. High conversions and yields were achieved for the synthesis of symmetric dialkylureas. This supported catalyst could also be easily separated and recovered after reaction.