Copper and Copper Oxide Nanoparticles in the Synthesis of N-Aryl Derivatives of Adamantane-Containing Amines

N-Arylation of several adamantane-containing amines with iodobenzene and its derivatives containing electron-donor and electron-withdrawing groups in para- and meta-positions was studied under catalysis by non-immobilized copper and copper oxide nanoparticles. It was shown that the best yields of the target N-aryl derivatives are achieved using the CuNPs 10/80 nm/rac-BINOL catalytic system when carrying out the reaction in DMSO at 110°C, which turned out to be the most universal. In some cases, it is possible to use other ligands like 2-acetylcyclohexanone and 2-isobutyrylcyclohexanone, as well as DMF as a solvent at 140°C. The maximum yields of N-aryl derivatives exceeded 90%, the dependence of the arylation reaction efficiency on the structure of adamantane-containing amines was shown, however, the effect of substituents in the aryl ring was not so significant. The leaching of copper into the solution during the model reaction was studied, it was shown that the degree of leaching depends on the nature of the ligand used. For comparison purposes, N-heteroarylation of adamantaneamine with trifluoromethyl-substituted 2-bromopyridines was studied, it was found that in this reaction copper leaching occurs to a greater extent. Using TEM, electronegraphy and EDX spectroscopy data, it was shown that 25 nm CuNPs are converted mainly into copper (I) oxide during the reaction, while the average size of the nanoparticles remains virtually unchanged.

adamantane, amines, amination, catalysis, aryl iodides, copper nanoparticles