Cp*Ir-catalyzed N-alkylation of amines with alcohols. A versatile and atom economical method for the synthesis of amines

A versatile and highly atom economical catalytic system consisting of [Cp*IrCl2](2)/NaHCO3 (Cp*=pentamethylcyclopentadienyl) for the N-alkylation of amines with primary and secondary alcohols as alkylating reagents has been developed. For example, the reaction of equimolar amounts of aniline and benzyl alcohol in the presence of [Cp*IrCl2](2) (1.0 mol % Ir) and NaHCO3 (1.0 mol %) in toluene at 110 degrees C gives N-benzylaniline in 94% yield. The present catalytic system is applicable to the N-alkylation of both primary and secondary amines, and only harmless water is produced as co-product. A wide variety of secondary and tertiary amines can be synthesized with high atom economy under mild and less-toxic conditions. One-pot sequential N-alkylation leading to tertiary amines bearing three different substituents is also described. (C) 2007 Elsevier Ltd. All rights reserved.