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.