Copper-Catalyzed Aerobic Oxidative Amination Of Arylboronic Acid With Aminal

Organic nitrogen compounds have a broadly applicable prospect in medicine, pesticide and chemical industry. Therefore, the development of simple and efficient methods for the synthesis of these compounds under mild conditions would be highly desirable in synthetic organic chemistry.In this dissertation, a simple new method for aerobic oxidative amination reaction of arylboronic acids with aminals to afford amine products via C-N bond activation has been developed. In this procedure, copper amide species could be generated via copper-catalyzed and acid-promoted C-N activation. Then transmetalation with arylboronic acids and subsequent reductive elimination would give the corresponding amine products. Lastly, copper species could be oxidated by O2 to regenerate Cu(II) and complete the catalytic cycle. With 10 mol% of Cu(acac)2 as a pre-catalyst,20 mol% of PhCO2H as an additive and air as oxidant, this coupling reaction could proceed very smoothly and give the desired products in moderate yield. It is noteworthy that this protocol could be performed in the absence of bases and ligands which often were necessary in the traditional C-N bond formation reaction and improve the atom economy of the reaction. The arylboronic acids containing electron-donating and electron-withdrawing groups of the benzene ring could transform into the corresponding products. In addition, the unsymmetrical aminal could also undergo the coupling reaction and furnish two different products in moderate yield. This result indicated that both the amine moieties of the aminal could participate in the coupling reaction and transform to their corresponding products under the mild reaction conditions.