Carbamic acid, [(2S)-2-aminopropyl]-, 1,1-dimethylethyl ester (9CI)

24424-99-5

19777-66-3

121103-15-9

GENERAL STEPS: To a mixture of methanol (64 mL) and water (16 mL) of (S)-1,2-diaminopropane dihydrochloride (16 g, 109 mmol), a methanolic solution (16 mL) of di-tert-butyl dicarbonate (28.5 g, 131 mmol) was added. The reaction mixture was cooled in an ice bath and a 4 N NaOH solution (35 mL, 140 mmol) was added slowly and dropwise over 2 hours. Subsequently, the mixture was gradually warmed to room temperature with continuous stirring for 20 hours. Upon completion of the reaction, the reaction mixture was filtered and the filtrate was concentrated to remove methanol. Ethyl acetate (200 mL), water (200 mL) and 1 M HCl (16 mL) were added sequentially to the concentrate. The organic and aqueous layers were separated and the aqueous layer was washed with ethyl acetate (200 mL). The combined organic extracts were washed with 0.04 M HCl (208 mL) and the organic phase was separated and discarded. The aqueous phases were combined and the pH was adjusted to 14 with 10 N NaOH (20 mL) and then extracted with dichloromethane (400 mL x 2). The organic extracts were combined, dried over anhydrous sodium sulfate, filtered and concentrated to afford the target product tert-butyl (S)-(2-aminopropyl)carbamate as a clear oil (8.0 g, 42% yield). Mass spectrum (ESI): calculated value C8H18N2O2, 174.1; measured value m/z, 175.2 [M + H]+. 1H NMR (500 MHz, CDCl3) δ 5.01 (broad peak, 1H), 3.24-3.09 (multiple peaks, 1H), 3.09-2.95 (multiple peaks, 1H), 2.92-2.84 (multiple peaks, 1H ), 1.45 (single peak, 9H), 1.35-1.19 (multiple peaks, 2H), 1.07 (double peak, J = 6.4 Hz, 3H).