C(NC(C)C)(C)C.[Li][CH2:9][CH2:10][CH2:11][CH3:12].[C:13]([N:20]1[CH2:25][CH2:24][CH:23]([C:26]([O:28][CH2:29][CH3:30])=[O:27])[CH2:22][CH2:21]1)([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14]>C1COCC1>[CH2:29]([O:28][C:26]([C:23]1([CH2:12][CH2:11][CH:10]=[CH2:9])[CH2:24][CH2:25][N:20]([C:13]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14])[CH2:21][CH2:22]1)=[O:27])[CH3:30]A mixture of THF (160 mL) and diisopropyl amine (9.92 mL, 70.8 mmol, 1.2 eq) was cooled to −78° C. and a 2.5 M solution of n-BuLi in heptanes (28.3 mL, 70.8 mmol, 1.2 eq) was added slowly. The solution was stirred for 15 min, warmed to 0° C. for 20 min and cooled back to −78° C. Ethyl N-Bocpiperidine-4-carboxylate (11 mL, 59 mmol, 1 eq.) in 10 mL of THF was added drop-wise and stirred for 40 min before it was warmed to rt. The reaction mixture was stirred for 12 h, transferred to a separatory funnel, quenched with 500 mL of water and extracted with ethyl acetate (2×300 mL). The combined organics were dried over Na2SO4 and concentrated under vacuum to give the title compound as a yellow oil (13.9 g, 76%).
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