[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][CH:11]([CH2:14][CH2:15][C:16]([OH:18])=O)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].CCN(C(C)C)C(C)C.CC(C)(C)C(Cl)=O.Cl.[CH3:36][NH:37][O:38][CH3:39]>C(Cl)Cl>[CH3:36][N:37]([O:38][CH3:39])[C:16](=[O:18])[CH2:15][CH2:14][CH:11]1[CH2:10][CH2:9][N:8]([C:6]([O:5][C:1]([CH3:2])([CH3:3])[CH3:4])=[O:7])[CH2:13][CH2:12]1
A solution of 3-(1-(tert-butoxycarbonyl)piperidin-4-yl)propionic acid (2.6 grams, 10 mmol, from Step A) and DIEA (4.4 mL, 25 mmol) in 50 mL CH2Cl2 was cooled to 0° C. Trimethylacetyl chloride (1.4 mL, 11 mmol) was added and the mixture was stirred for 1 h. Solid N,O-dimethylhydroxylamine hydrochloride (1.4 grams, 15 mmol) was added and the mixture was warmed to rt and stirred for 16 h. The solvent was removed and the product was purified by flash chromatography (125 grams silica, 2/1 hexane/EtOAc eluant) to give 1.5 grams (50%) of the title compound. 1H NMR (300 MHz, CDCl3). δ1.05-1.18 (m, 2H), 1.45 (s, 9H), 1.53-1.75 (m, 4H), 2.4-2.5 (t, 2H), 2.6-2.77 (m, 2H), 3.18 (s, 3H), 3.63 (s, 3H), 4.0-4.15 (m, 2H).
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