[NH:1]1[CH2:6][CH2:5][CH:4]([CH:7]2[CH2:12][CH2:11][NH:10][CH2:9][CH2:8]2)[CH2:3][CH2:2]1.[CH3:13][C:14]([O:17][C:18](ON=C(C1C=CC=CC=1)C#N)=[O:19])([CH3:16])[CH3:15].C(=O)([O-])[O-].[K+].[K+]>O1CCCC1.C(Cl)(Cl)Cl>[N:1]1([C:18]([O:17][C:14]([CH3:16])([CH3:15])[CH3:13])=[O:19])[CH2:6][CH2:5][CH:4]([CH:7]2[CH2:12][CH2:11][NH:10][CH2:9][CH2:8]2)[CH2:3][CH2:2]1To 4,4′-bipiperidine (5.48 g, 32.6 mmol) in tetrahydrofuran (160 mL) and chloroform (160 mL) was added BOC-ON (4.01 g, 16.2 mmol) in tetrahydrofuran (90 mL) dropwise over an 8 hour period. The reaction was then concentrated and purified by chromatograpy on SiO2. The residue was taken up in 1M KHSO4 (250 mL) and washed with diethyl ether (three times). Potassium carbonate (38.0 g, 275 mmol) was added to the aqueous layer which was subsequently extracted with chloroform (three times), dried (MgSO4), and concentrated to provide 1,1-dimethylethyl 4,4′-bipiperidine-1-carboxylate (1.98 g, 7.40 mmol, 45%). 1H NMR (400 MHz, CDCl3) δ ppm 1.06-1.18 (m, 6 H), 1.42 (s, 9 H), 1.58-1.69 (m, 6 H), 2.50-2.61 (m, 4 H), 3.06 (d, J=12.1 Hz, 2 H), 4.08 (br s, 1 H).
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