Sodium borohydride → tert-butyl[(2S)-1-{[tert-butyl(diphenyl)silyl]oxy}-6-hydroxyhexan-2-yl]carbamate

Participants

Reaction Steps

To a stirred solution of the material from Step 3 (128 g, 219 mmol) in 2-propanol (1800 mL) and water (180 mL) at room temperature was added sodium borohydride (8.28 g, 219 mmol). The reaction mixture was stirred at room temperature overnight. Additional 2 g of sodium borohydride was added and stirred at room temperature for an additional 4 hours. The reaction mixture was concentrated to ⅓ volume and diluted with EtOAc and 1 N NaOH (100 mL). The reaction mixture was partitioned, and extracted with EtOAc. The combined organics were washed with brine, dried over MgSO4, filtered and concentrated. The residue was purified by flash chromatography on silica gel using EtOAc-hexanes (0 to 50%) to afford 65 g of the title compound. 1H NMR (CHCl3-d): δ 7.67-7.62 (m, 4H), 7.45-7.35 (m, 6H), 4.72-4.65 (b, 1H), 3.72-3.62 (m, 2H), 3.60-3.52 (m, 3H), 1.62-1.42 (m, 4H), 1.42 (s, 9H), 1.42-1.23 (m, 2H), 1.05 (s, 9H).

Provenance & Evidence