Mild N‐Alkylation of Amines with Alcohols Catalyzed by the Acetate Ru(OAc)2(CO)(DiPPF) Complex

The acetate complex Ru(OAc)2(DiPPF) (2) obtained from Ru(OAc)2(PPh3)2 (1) and 1,1′‐bis(diisopropylphosphino)ferrocene (DiPPF) reacts cleanly with formaldehyde affording Ru(OAc)2(CO)(DiPPF) (3) in high yield. The monocarbonyl complex 3 (0.4‐2 mol %) efficiently catalyzes the N‐alkylation of primary and secondary alkyl and aromatic amines using primary alcohols ROH (R=Et, nPr, nBu, PhCH2) under mild reaction conditions (30–100 °C) with an alcohol/amine molar ratio of 10‐100. Formation of the monohydride RuH(OAc)(CO)(DiPPF) (4) has been observed by reaction of 3 with iPrOH in the presence of NEt3 at RT through an equilibrium reaction. Amico rutenio: The complex Ru(OAc)2(CO)(DiPPF), easily prepared by carbonylation of Ru(OAc)2(DiPPF) with H2CO, efficiently catalyzes the alkylation of primary and secondary amines with alcohols under mild reaction conditions. Addition of a suitable amount of trifluoroacetic acid increases the rate of reaction. Evidence of the formation of the monohydride RuH(OAc)(CO)(DiPPF) species is provided.