To a solution of 1-(4-benzyloxy-benzenesulfonyl)-5-methoxy-piperidine-2-carboxylic acid allyloxy-amide (0.090 g, 0.20 mmol), triethylammonium formate (0.28 mL of a 3M solution in water, 0.83 mmol) and acetonitrile (1.1 mL) was added tetrakistriphenylphosphine palladium. After stirring for 15 min at 80° C., the mixture was cooled to room temperature and concentrated in vacuo. The residue was diluted with ether and extracted 2× into 1 M NaOH. The combined aqueous layers were washed 2× with ether, acidified with 1M HCl and extracted 3× with ethyl acetate. The combined organic layers were dried over Na2SO4, filtered and concentrated. Purification of the residue by silica gel chromatography eluting with ethyl acetate afforded 0.025 g of 1-(4-benzyloxy-benzenesulfonyl)-5-methoxy-piperidine-2-carboxylic acid hydroxyamide as a yellow solid after trituration from CH2Cl2-hexane:
