Enhancing the efficiency of the ruthenium catalysts in the reductive amination without an external hydrogen source

Addition of iodide to the ruthenium chloride catalysts strongly increases its activity. • Ruthenium catalyst’s activity can be increased by a factor of 15 by adding iodide. • Catalyst TONs in the direct reductive amination achieve 9000. • Sterically hindered camphoryl amine was prepared. • In some cases, further increase of the activity might be achieved by phosphine addition. Catalytic reductive reactions are essential for laboratory and industrial-scale organic synthesis. However, the nowadays trend is the development of new, progressively more complicated reducing systems, which hinders the application of such highly efficient approaches in practice. Another way to achieve highly active systems is enhancing the activity of the earlier developed catalysts with simple structures. Herein we demonstrated a significant increase (up to 15-fold) in the catalytic activity of ruthenium catalysts in the reductive amination after the addition of iodide to the reaction mixture. Catalyst turnover numbers up to 9000 were achieved with preparative yields of the products. The plausible reasons for this effect were formulated.