Studies On The Nitration Of Aromatic Amines And The Synthesis Of A-Trilfuoromethyl Ketones

The regioselective ortho-nitration of aromatic amines and the synthesis of a-trifluoromethyl (hetero)aryl ketones have been investigated in this thesis, which is divided into two sections as following.Section one focuses on a regioselective ortho-nitration of N-phenyl carboxamides and primary anilines. o-Nitroanilines are key intermediates used in the synthesis of benzimidazoles and1,2-diamines. Mainly para-nitrated product is obtained via nitration of aniline using the mixed acid (H2SO4/HNO3). And most existing nitrating reagents are strong oxidants, which limit their application for easily oxidized anilines. Therefore, the development of mild and regioselective nitration methods is of industrial value.In this paper, after screening nitrating reagents, solvents and temperature, we determined using1equiv Bi(NO3)3-5H2O,6-7equiv AC2O, CH2Cl2as solvent at room temperature for1-5h as the optimal reaction conditions. And twenty-one o-nitro aromatic amines were synthesized in a one-pot reaction, the isolated yield is30%-98%. We also arrived at the possible mechanism for the regioselective ortho-nitration.Section two focuses on a copper-catalyzed trifluoromethylation of aryl(heteroaryl) enol acetates. Trifluoromethylated compounds have been widely utilized in the fields of pharmaceuticals, agrochemicals and functional materials since the CF3group(s) can alter their polarity, lipophilicity and metabolic stability. Hence, it has been of great synthetic interest to develop new methods for the incorporation of CF3group(s) into organic molecules.An efficient method for the Cul-catalyzed synthesis of a-trifluoromethyl ketones via the addition of CF3radical to aryl(heteroaryl) enol acetates by using CF3SO2Na has been developed. The method employs readily available chemicals and the reaction is experimentally simple, rapidly occurring at ambient temperature and exhibiting wide functional group tolerance and certain heteroaromatics. In addition, experimental results indicated that the CF3radical is involved in the transformation by use of a radical scavenger2,2,6,6-tetramethyl-l-piperdinyloxy (TEMPO).