Cyclobutadiene Metal Complexes: A New Class of Highly Selective Catalysts. An Application to Direct Reductive Amination

A catalyst of a new type, cyclobutadiene complex [(C4Et4)Rh(p-xylene)]PF6, was found to promote selective reductive amination in the presence of carbon monoxide under mild conditions (1-3 bar, 90 degrees C). The reaction demonstrated perfect compatibility with a wide range of functional groups prone to reduction by conventional reducing agents. The developed system represents the first systematic investigation of cyclobutadiene metal complexes as catalysts.