(S)-Alaninol (2.0 g, 26.6 mmol) was dissolved in aqueous NaOH solution (50 ml, 1 M) and was cooled in an ice/water bath. A solution of di-tert-butyldicarbonate (6.5 g, 30.0 mmol) in dioxane (30 ml) was added and the mixture was stirred for 3 h. The mixture was then allowed to separate. The aqueous layer was acidified to pH ≈ 8 using a saturated NH₄Cl solution and extracted with ethyl acetate (4 × 30 ml). The organic layer and ethyl acetate extracts were combined and the solvents were removed under reduced pressure. The obtained residue was extracted with ethyl acetate/hexane (1:2) mixture, filtered and the solvent were removed under reduced pressure. The obtained product was used in the subsequent step without further purification. Yield 3.3 g (71%).

¹H NMR (400 MHz, 298 K, CDCl₃) δ_H 4.78 (1H, s, NH), 3.73 (1H, s, CH), 3.59 (1H, dd, ³J_HH = 10.8 Hz, ²J_HH = 3.5 Hz, CH₂), 3.47 (1H, dd, ³J_HH = 10.8 Hz, ²J_HH = 6.0 Hz, CH₂), 3.06 (1H, s, OH), 1.42 (9H, s, ^tBu), 1.12 (3H, d, ³J_HH = 6.8 Hz, CHCH₃).

¹³C NMR (100 MHz, 298 K, CDCl₃) δ_C 156.31 (C=O), 79.50 (C(CH₃)₃), 66.54 (CH₂), 48.38 (CH), 28.40 (C(CH₃)₃), 17.33 (CHCH₃).

MS (ESI⁺) m/z 198.2 ([M+Na]⁺)

MS (ESI^-) m/z 174.8 ([M]^-)

IR (cm^-1) ν 3445, 3340, 2977, 2938, 2878, 1675, 1650, 1531, 1456, 1393, 1363, 1344, 1313, 1277, 1251, 1160, 1102, 1060, 1025, 934, 915, 880, 843, 781, 754.

A. Benalil, B. Carboni and M. Vaultier, Tetrahedron, 1991, 47, 8177-8194. http://dx.doi.org/10.1016/S0040-4020(01)91013-0