C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.[C:20]([Br:24])(Br)(Br)[Br:21].O=[C:26]1[CH2:31][CH2:30][N:29]([C:32]([O:34][C:35]([CH3:38])([CH3:37])[CH3:36])=[O:33])[CH2:28][CH2:27]1>ClCCl>[Br:21][C:20]([Br:24])=[C:26]1[CH2:31][CH2:30][N:29]([C:32]([O:34][C:35]([CH3:38])([CH3:37])[CH3:36])=[O:33])[CH2:28][CH2:27]1To a stirred solution of triphenylphosphine (155.6 g, 0.59 mol) in dry dichloromethane (870 mL) at 0° C. was added carbon tetrabromide (100.86 g, 0.304 mol) portionwise. The mixture was stirred at RT for 30 min and then cooled to −78° C. A solution of tert-butyl 4-oxopiperidine-1-carboxylate (30 g, 0.15 mol) in CH2Cl2 (90 mL) was added dropwise and the reaction was stirred at −78° C. for 30 min and then at RT overnight. The mixture was filtered and the filtrate was evaporated to dryness. Diethyl ether was added and the mixture was filtered again. The filtrate was evaporated to dryness to give the title compound (64 g). 1H NMR (500 MHz, CDCl3): δ 3.44 (m, 4H), 2.46 (m, 4H), 1.47 (s, 9H).
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