[1,1-Dioxo-(3R,4S)-4-[(R)-1-phenyl-ethylamino]-tetrahydrothiophen-3-yl]-[(S)-3-(4-fluoro-benzyl)-piperidin-1-yl]-methanone → [(3R,4S)-4-Amino-1,1-dioxo-tetrahydrothiophen-3-yl]-[(S)-3-(4-fluorobenzyl)-piperidin-1-yl]-methanone

[1,1-Dioxo-(3R,4S)-4-[(R)-1-phenyl-ethylamino]-tetrahydrothiophen-3-yl]-[(S)-3-(4-fluoro-benzyl)-piperidin-1-yl]-methanone (790 mg, 1.72 mmol), palladium hydroxide (20 weight % on carbon, dry basis; 1.1 g) and methanol (50 mL) were combined in a pressure bottle and shaken under a hydrogen atmosphere (55-60 psig) for 20.5 h. The mixture was filtered through Celite, and the solids were washed thoroughly with methanol. The filtrate was concentrated to give the product as a solid (660 mg, quantitative), used without further purification.