The Formation of a Novel Pd/C−Ethylenediamine Complex Catalyst:  Chemoselective Hydrogenation without Deprotection of the O-Benzyl and N-Cbz Groups

A Pd/C catalyst formed an isolable complex with ethylenediamine employed as the catalytic poison via one-to-one interaction between Pd metal and ethylenediamine, and this complex catalyst Pd/C(en) chemoselectively hydrogenated a variety of reducible functionalities such as olefin, acetylene, nitro, benzyl ester, and azido in the presence of an O -benzyl or N -Cbz protective group. These findings reinforce the versatility potential of O -benzyl and N -Cbz as protective groups in organic synthesis, and the Pd/C(en) catalyst has been identified as a novel and chemoselective catalyst for the hydrogenation.