Palladium Catalytic Amide Carbonylation Reaction Synthesis Of Amino Formic Acid Ester And N, N '- Diphenyl Urea Compounds

Carbamates and N,N’-disubstituted ureas are important nitrogen-containing carbonyl compounds which are commonly encountered in the structure of natural products and biologically active compounds. Carbamates are pivotal precursors for the synthesis of pesticides, fungicides, herbicides and drugs. N,N’-disubstituted ureas are widely used as agrochemicals, dyes, antioxidants and HIV inhibitors. In addition, they are also widely applied as key intermediates in organic synthesis. Owning to its contribution in organic chemistry, the synthesis of these compounds is of great significance. Efficient approaches to carbamates and ureas were achieved by coupling of amines with phosgene and its derivatives. However, the extensive application of these highly toxic reagents would make serious environmental problems and equipment corrosion. Therefore, intense effort has been focused on the development of non-phosgene processes for the synthesis of carbamates and N,N’-disubstituted ureas.Transition-metal-catalyzed carbonylation reaction of amines has attracted considerable attention as powerful method for the construction of carbamates and N,N’-disubstituted ureas. Perhaps the most widely applicable metal-catalyzed method developed to date is the palladium-catalyzed carbonylation reactions. However, these systems are apparently limited to aliphatic amines, high temperature and high pressure of CO. Therefore, the efforts to find new catalytic systems for a wide range of aromatic amines under mild conditions are still highly desirable. In this paper, the synthesis methods to afford carbamates and N,N’-disubstituted ureas have been reviewed. Then, Pd-catalyzed carbonylation of aromatic amines has been studied and switchable access to N-phenylcarbamate and N,N’-diphenylurea has been achieved by reagent control under mild reaction conditions。...