[C:1]([C:4]1(C)[CH2:9][CH2:8][N:7]([C:10]([O:12][C:13]([CH3:16])([CH3:15])[CH3:14])=[O:11])[CH2:6][CH2:5]1)(=O)N.[OH-].[K+].Br[N:21]1C(C)(C)C(=O)N(Br)C1=O.S([O-])([O-])=O.[Na+].[Na+].[O-]P([O-])([O-])=O.[K+].[K+].[K+]>C(#N)C.O.C(OCC)(=O)C>[NH2:21][C:4]1([CH3:1])[CH2:9][CH2:8][N:7]([C:10]([O:12][C:13]([CH3:16])([CH3:15])[CH3:14])=[O:11])[CH2:6][CH2:5]1To a suspension of tert-butyl 4-carbamoyl-4-methylpiperidine-1-carboxylate (2.52 g, 10.4 mmol) in acetonitrile (7.6 mL) and water (23.4 mL) was added KOH (2.63 g, 46.8 mmol) at 0° C. Then 1,3-dibromo-5,5-dimethylhydantoin (1.64 g, 5.72 mmol) was added in one portion at 0° C. and after stirring at 0° C. for 30 minutes the solution was allowed to warm up to room temperature and stirred for 1 hour. Sodium sulfite (131 mg, 1.04 mmol) was added and the mixture was stirred for 15 minutes at room temperature, then ethyl acetate was added and the reaction was cooled to 10° C. K3PO4 (2.34 g, 11.0 mmol) was added and the mixture was warmed up to room temperature and extracted with ethyl acetate. The organic layers were washed with brine, dried over sodium sulfate, filtered and evaporated to give the title compound (2.1 g, 94%) as a colourless oil. MS ISP (m/e): 215.3 [(M+H)+].
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