Metal-Mediated Organocatalysis in Water: Serendipitous Discovery of Aldol Reaction Catalyzed by the [Ru(bpy)2(nornicotine)2]2+ Complex

The [Ru(bpy)2(Nor)2]2+complex (Nor = nornico-tine) is an efficient catalyst for the aldol reaction of acetone withactivated benzaldehydes in a buffered aqueous solution. The metalplays the role of an activator for the nornicotine organocatalystligands. The resulting catalytic activity is potentiated by a factor ofabout 4.5 as compared to freenornicotine. Similar rateenhancements can be achieved by using Zn(II) cations as theactivator. The observations are rationalized with the reducedbasicity of the pyrrolidine N in nornicotine due to the enhancedelectron withdrawal of the metal-complexed pyridyl moiety.

Automated summary

The [Ru(bpy)2(Nor)2]2+ complex is an efficient catalyst for the aldol reaction of acetone with activated benzaldehydes in a buffered aqueous solution. The role of the metal as an activator for nornicotine organocatalyst ligands enhances catalytic activity by about 4.5 times compared to free nornicotine. The study provides insights into the synergistic effect of organic catalysts and metals.