[C:1]([O:5][C:6]([NH:8][C@H:9]([CH3:13])[C:10](O)=[O:11])=[O:7])([CH3:4])([CH3:3])[CH3:2].F[B-](F)(F)F.N1(O[C:29](N(C)C)=[N+:30](C)[CH3:31])C2C=CC=CC=2N=N1.Cl.CNC.C(N(CC)C(C)C)(C)C>ClCCl.O>[C:1]([O:5][C:6](=[O:7])[NH:8][C@@H:9]([C:10](=[O:11])[N:30]([CH3:31])[CH3:29])[CH3:13])([CH3:4])([CH3:3])[CH3:2]
(R)-2-(tert-Butoxycarbonylamino)propanoic acid (1.0 g, 5.3 mmol) and O-benzotriazol-1-yl-N,N,N′,N′-tetramethyluronium tetrafluoroborate (1.8 g, 5.6 mmol) were dissolved in 13 mL of dichloromethane. Dimethylamine hydrochloride (0.64 g, 7.8 mmol) and N,N-diisopropylethylamine (3.6 mL, 20.8 mmol) were added and the mixture was stirred at room temperature for 16 h. The reaction mixture was diluted with dichloromethane and water was added. The layers were separated and the aqueous layer was extracted once more with dichloromethane. The combined organic layers were washed with sodium chloride solution, dried over sodium sulfate and concentrated. The residue was purified by silica gel chromatography (ethyl acetate/hexanes) to give 1.16 g (100%) of ((R)-1-dimethylcarbamoyl-ethyl)-carbamic acid tert-butyl ester.
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