ABSTRACT
Steve S. Y Wanga, Jun Lia, Karen TenHuisena, Jale Muslehiddinoglua, Srinivas Tummala,a San Kianga, and Jianping J. P. Chenb
aBristol-Myers Squibb Company, Pharmaceutical Research Institute, New Brunswick, NJ 08903
bEngelhard Corporation, Beachwood R&D Center Beachwood, OH 44122
Abstract Reductive debenzylation has been widely used in the fine chemical and pharmaceutical industries. When an aromatic halogen is present, selective debenzylation verses dehalogenation has been a challenging task. In our earlier studies, transfer hydrogenolysis under different solvent, pH and salt conditions was investigated. For gaseous hydrogenolysis, a variety of palladium catalysts with different metal loadings, oxidation states and support materials were evaluated. A newly developed DeLinkTM 10%Pd/CPS4 catalyst had the desired selectivity to convert (S) to product (A) in this reaction. In contrast, the low metal loading 3%Pd/C (Engelhard nonstandard catalyst) readily overhydrogenated the debenzylated product (A), generating the dechlorinated byproduct (B).
