Development of Carbon‐Neutral Cellulose‐Supported Heterogeneous Palladium Catalysts for Chemoselective Hydrogenation

Abstract

Abstract Palladium catalysts immobilized on cellulose particles (Pd/CLP) and on a cellulose‐monolith (Pd/CLM) were developed. These composites were applied as hydrogenation catalysts and their catalyst activities were evaluated. Although both catalysts catalyzed the deprotection of benzyloxycarbonyl‐protected aromatic amines (Ar‐ N‐ Cbz) and aromatic benzyl esters (Ar‐CO 2 Bn), only Pd/CLM could accomplish the hydrogenolysis of aliphatic‐ N‐ Cbz and aliphatic‐CO 2 Bn protective groups. The difference in the physical structure of the cellulose supports induced unique chemoselectivity. Aliphatic‐ N‐ Cbz and aliphatic‐CO 2 Bn groups were tolerated under the Pd/CLP‐catalyzed hydrogenation conditions, while Ar‐ N‐ Cbz, Ar‐CO 2 Bn, alkene, alkyne, azido and nitro groups could be smoothly reduced.