[C:1]([CH:4]1[CH2:9][CH:8]([C:10]([O:12][CH2:13][CH3:14])=[O:11])[CH2:7][CH2:6][N:5]1[C:15]([O:17][CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)=[O:16])(=O)[NH2:2].N1C=CC=CC=1.O=S(Cl)Cl>>[C:1]([CH:4]1[CH2:9][CH:8]([C:10]([O:12][CH2:13][CH3:14])=[O:11])[CH2:7][CH2:6][N:5]1[C:15]([O:17][CH2:18][C:19]1[CH:20]=[CH:21][CH:22]=[CH:23][CH:24]=1)=[O:16])#[N:2]1-Benzyl 4-ethyl 2-carbamoylpiperidine-1,4-dicarboxylate (2.4 g, 7.18 mmol) was dissolved in pyridine (50 mL, 618.21 mmol). The mixture was cooled on an ice bath and SOCl2 (3.14 mL, 43.07 mmol) was added dropwise and left overnight at room temperature. The reaction mixture was evaporated and partitioned between diluted HCl and DCM. The aqueous layer was extracted with DCM and the combined organic layer was washed with water, dried over Na2SO4 and evaporated. Crude 1-benzyl 4-ethyl 2-cyanopiperidine-1,4-dicarboxylate (2.25 g, 99%) was isolated. 1H NMR (400 MHz, dmso) δ 1.21 (t, 3H), 1.54-1.66 (m, 1H), 1.98-2.12 (m, 2H), 2.29-2.37 (m, 1H), 2.83-2.91 (m, 1H), 3.04-3.16 (m, 1H), 3.83-3.91 (m, 1H), 4.02-4.18 (m, 2H), 5.13 (s, 2H), 5.25-5.31 (m, 1H), 7.28-7.40 (m, 5H).
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