To a solution of (3R*,4S*,5S*)-3-amino-5-(3-fluoro-4-nitro-benzyl)-1,1-dioxo-hexahydro-1lambda*6*-thiopyran-4-ol hydrochloride (0.14 g, 0.39 mmol) in MeOH-CH2Cl2 1:1 (3 mL) was added NaOAc (0.065 g, 0.78 mmol) and 3-tert-butyl-benzaldehyde (0.07 g, 0.43 mmol). The reaction mixture was stirred at 25° C. for 0.5 h before NaBH3CN (0.039 g, 0.59 mmol) was added followed by stirring for 16 h. The reaction mixture was acidified with 1N aq. HCl, stirred for 15 min, basified with K2CO3-solution and extracted with EtOAc. The combined organic layers were washed with brine, dried over MgSO4 and evaporated. The title compound was obtained after purification by flash-chromatography on silica gel (hexane-CH2Cl2-MeOH 20:20:1 to 1:20:5) as a light yellow foam: TLC (EtOAc) Rf=0.45; HPLC RtA=1.78 min; ESIMS [M+H]+=465; 1H NMR (400 MHz, CDCl3): δ 8.02 (t, 1H), 7.1-7.4 (m, 6H), 4.18 (s, 1H), 3.88 (d, 1H), 3.78 (d, 1H), 3.64 (m, 1H), 3.41 (ddd, 1H), 3.24 (ddd, 1H), 3.12 (dt, 1H), 3.00 (dd, 1H), 2.84, (m, 2H), 2.69 (m, 2H), 2.44 (m, 1H), 1.33 (s, 9H).
