Transalkylation Reaction. Homogeneous Catalytic Formation of C-N Bonds

Article abstract of DOI:10.1021/ja00288a015

We have performed kinetic and mechanistic studies on homogeneous ruthenium-catalyzed transalkylation of tertiary amines.From these studies we have derived a kinetic expression for transalkylation catalysis based on initial reaction rates.We find that transalkylation proceeds most efficiently in alcoholic solvents (e.g., MeOH or EtOH), under a slight pressure of CO, with a mixed-metal, iron-ruthenium catalyst.The mechanism appears to be in one which a metal cluster of at least two and most probably three atoms binds the amine through insertion into an α C-H bond to give a metallazacyclopropane or metal-iminium complex.Nucleophilic attack by free amine on the complex, or an immediate derivative, follows, and subsequent rearrangement of the intermediate formed gives transalkylation products.The catalyst system has been tested as a synthetic tool for the oligomerization and cyclization of tertiary diamines.These preliminary studies have been quite succesful.Thus, N,N,N',N'-tetramethylethylenediamine can be transformed into Me3N and N,N'-dimethylpiperazine with good conversion and high selectivity.N,N,N',N'-Tetraethylethylenediamine can be transformed into Et3N and the linear, perethyl, ethylenediamine dimer, trimer, tetramer, and pentamer with excellent conversion.