Mild N-Alkylation of Amines with Alcohols Catalyzed by Acetate Ruthenium Complexes

The formation of C-N bonds for the preparation of amines compounds is a reaction of high relevance for the synthesis of bulk and fine chemicals (1). The preparation of several drug molecules involves N-substitution transformations that are usually performed by reaction of amines with alkylating agents or via reductive amination. In this context, the catalytic Nalkylation of amines using environmentally friendly alcohols as alkylating reagents and affording water as only byproduct, is an attractive atom-economic way for the C-N bond formation (2,3). We report here the straightforward synthesis of the carboxylate ruthenium complexes of formula Ru(OAc)2(diphosphane)(CO)n (n = 0, 1). These compounds are efficient catalysts for the N-alkylation of amines using primary alcohols under mild reaction conditions, with an alcohol / amine molar ratio of 10-100. Evidence has been provided that in catalysis a monohydride species is formed through an equilibrium reaction.