Organocatalytic Knoevenagel Condensations by Means of Carbamic Acid Ammonium Salts
摘要:
fThe Knoevenagel condensation between an active methylene compound and an aromatic aldehyde with a carbamic acid ammonium salt used as an organocatalyst gave the desired Knoevenagel products in up to 98% yield. The reaction occurred at rt and in a short reaction time under solvent-free conditions. In addition, no extraction, wash, or chromatography steps were needed to obtain a high-purity Knoevenagel product.
Ureaderivatives are obtained in mild to good yield from the reactions of primary aliphatic amines with CO2 in the absence of any catalysts, organic solvents or other additives. To optimize reaction conditions, experimental variables including temperature, pressure, the concentration of amine, reaction time etc. were studied. Satisfactory yields were obtained at the optimized conditions that are comparable
ammonium carbamates with trimethylchlorosilane. Trimethylsilyl NN-dimethylcarbamate can be used for silylation of alcohols,phenols, and carboxylicacids. The silycarbamates react with carboxylicacid halides to give the corresponding acide amides. The reaction of trimethylsilyl carbamates with carboxylicanhydrides give the corresponding silyl carboxylate and acid amide, while the reaction with dicarboxylic
Direct use of CO2 for O-arylcarbamate synthesis via mild Cu(II)-catalyzed aerobic C-H functionalization in pincer-like macrocyclic systems
作者:Elise Bernoud、Anna Company、Xavi Ribas
DOI:10.1016/j.jorganchem.2017.02.004
日期:2017.9
Cu(II)-catalyzed C-H functionalization for the synthesis of O-arylcarbamates in a model pincer-like arene substrate using CO2 gas as C1-synthon is shown to proceed via aryl-Cu(III) intermediate species at roomtemperature. Indeed, stoichiometric experiments have been performed starting from an isolated Cu(III) complex and carbamic ammonium salts. A catalytic version has been then developed using a