C(OC([NH:11][C@H:12]([C:14]1[CH:26]=[CH:25][C:17]([C:18]([O:20][C:21]([CH3:24])([CH3:23])[CH3:22])=[O:19])=[CH:16][CH:15]=1)[CH3:13])=O)C1C=CC=CC=1>C(O)C.C(O)(=O)C.[C].[Pd]>[NH2:11][C@H:12]([C:14]1[CH:26]=[CH:25][C:17]([C:18]([O:20][C:21]([CH3:23])([CH3:22])[CH3:24])=[O:19])=[CH:16][CH:15]=1)[CH3:13]To a stirred solution of tert-butyl 4-((1S)-1-{[(benzyloxy)carbonyl]amino}ethyl)benzoate (step 2, 3.48 g, 9.8 mmol) in a mixture of ethanol (25 mL) and acetic acid (25 mL) was added 10% palladium-carbon (400 mg). The mixture was stirred at room temperature for 2 h under hydrogen atmosphere. The palladium catalyst was removed by filtration and washed with ethanol (100 mL). The filtrate was concentrated under reduced pressure and the residue was partitioned between ethyl acetate (200 mL) and saturated sodium bicarbonate aqueous solution (200 mL). The organic phase was separated and the aqueous phase was extracted with ethyl acetate (200 mL). The combined organic extracts were washed with brine (200 mL) and dried (sodium sulfate), and concentrated to give 2.02 g (93%) of the title compounds as white solids: 1H-NMR (CDCl3) δ 7.95 (2H, d, J=8.3 Hz), 7.39 (2H, d, J=8.3 Hz), 4.22–4.12 (1H, dq, J=7.3, 6.6 Hz), 1.80 (2H, br.s), 1.58 (9H, s), 1.38 (3H, d, J=6.6 Hz).
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