[C:1]([O:5][C:6]([NH:8][C:9]([CH3:14])([C:11](O)=[O:12])[CH3:10])=[O:7])([CH3:4])([CH3:3])[CH3:2].[CH3:15][N:16]1CCOCC1.C(OC(Cl)=O)C(C)C>C1COCC1>[C:1]([O:5][C:6]([NH:8][C:9]([CH3:14])([C:11]([NH:16][CH3:15])=[O:12])[CH3:10])=[O:7])([CH3:4])([CH3:3])[CH3:2]N-(tert-butoxycarbonyl)-2-methylalanine (2.87 g, 14.13 mmol) was dissolved in THF (20 ml) and cooled to −10° C. (acetone/ice). N-methylmorpholine (2.14 g, 21.2 mmol) was added followed by iso-butylchloroformate (2.12 g, 15.5 mmol, 1.1 equivalents) over a period of 3 minutes. The reaction mixture was allowed to stir for 10 minutes, split in two equal halves (approximately 12 ml each). One sample was treated with methylamine in THF (5 ml of 2.0M solution) and the resulting mixture was evaporated to dryness. The residues were re-dissolved in dichloromethane (30 ml), washed with water, saturated aqueous sodium hydrogen carbonate, water, dried over magnesium sulfate and evaporated to dryness to give N2-(tert-butoxycarbonyl)-N1,2-dimethylalaninamide (0.67 g, 42.6%), which was used without further purification, 1H NMR Spectrum: (DMSO-d6) 1.29 (s, 6H), 1.37 (s, 9H), 2.50 (s, 3H), 6.57 (br s, 1H), 6.93 (br s, 1H)
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