N-alkylation of amines by homogeneous ruthenium complexes in the presence of free diphosphines

Chemoselective N-alkylation of amines by ruthenium complexes in the presence of free diphosphine ligands under mild conditions is described. Octyl amine and aniline were chosen as aliphatic and aromatic amines to investigate the effect of different phosphines, reaction times, and temperature on conversion, as well as selectivity towards related secondary and tertiary amines. After optimization of the reaction conditions, this catalytic system was used for N-alkylation of other amines and has shown moderate to very good yields. The reaction products were monitored by GC–MS. The crystal structure of [Ru(NO3)2CO(PPh3)2] with a monodentate and a bidentate nitrate was determined by X-ray crystallographic analysis.