Sodium Bromate → tert-butyl[(5S)-5-[(tert-butoxycarbonyl)amino]-6-{[tert-butyl(diphenyl)silyl]oxy}hexanoyl]carbamate

Participants

Reaction Steps

To a stirred solution of the material from Step 2 (339.5 g, 595 mmol) in EtOAc (1000 mL) and H2O (1400 mL) at room temperature were added sodium bromate (250 g, 1657 mmol) and ruthenium oxide hydrate (3 g, 19.86 mmol). The reaction mixture was stirred at room temperature overnight, 50% of conversion. The mixture was then heated at 55° C. overnight. Additional sodium bromate (100 g) was added and the resulting mixture was heated at 40° C. for 12 hours. Upon cooling to room temperature, the reaction mixture was filtered through celite. The filtrate was extracted with EtOAc (2×). The combined organics were then washed with aqueous sodium bisulfite and brine, and dried over MgSO4. The filtrate was treated with charcoal (Darco® G-60, Norit Americas Inc., Marshall, Tex.) and filtered through a pad of silica gel. The filtrate was concentrated in vacuo and the residue was purified by flash chromatography on silica gel using EtOAc-hexanes to yield 128 g of the title compound as a colorless viscous oil. 1H NMR (CHCl3-d): δ 7.67-7.62 (m, 4H), 7.58-7.52 (b, 1H), 7.42-7.35 (m, 6H), 4.72-4.65 (b, 1H), 3.70-3.62 (m, 2H), 3.58-3.52 (m, 1H), 2.76-2.62 (m, 2H), 1.75-1.55 (m, 2H), 1.48 (s, 9H), 1.42 (s, 9H), 1.32-1.23 (m, 2H), 1.05 (s, 9H).

Provenance & Evidence