Palladium hydroxide

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of the compound (10.5 g) obtained in step 1 in 20% palladium hydroxide on carbon (50% wet, 2.63 g) in ethanol (250 mL) was stirred under a hydrogen atmosphere (1 atm) at room temperature for 14 hr. The catalyst was filtered off, and the filtrate was concentrated under reduced pressure. To a solution of the obtained residue in acetonitrile (50 mL) were added triethylamine (4.6 mL) and Boc2O (7.14 g), and the mixture was stirred at room temperature for 14 hr. The reaction mixture was poured into water, and the resultant product was extracted with ethyl acetate. The organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and brine and dried, and the solvent was evaporated under reduced pressure. The obtained residue was separated and purified by silica gel column chromatography (solvent gradient; 10→20% ethyl acetate/hexane) to give 4-ethyl 1-tert-butyl (3R*,4S*)-3-phenylpiperidine-1,4-dicarboxylate (8.31 g, 76%) as a colorless oil. The catalyst was filtered off the filtrate was concentrated under reduced pressure To a solution of the obtained residue in acetonitrile (50 mL) were added triethylamine (4.6 mL) and Boc2O (7.14 g) The reaction mixture was poured into water the resultant product was extracted with ethyl acetate The organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and brine dried the solvent was evaporated under reduced pressure The obtained residue was separated purified by silica gel column chromatography (solvent gradient; 10→20% ethyl acetate/hexane)