tert-butyl (3R)-4-hydroxy-3-[(2-methylpropan-2-yl)oxycarbonylamino]butanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Triphenylphosphine (1.07 g, 4 mmol), imidazole (277 mg, 4 mmol) and iodine (1.02 g, 4 mmol) were dissolved into methylene chloride (12 mL) under nitrogen atmosphere. (R)-tert-butyl 3-(tert-butoxycarbonylamino)-4-hydroxybutanoate (275 mg, 1 mmol) was dissolved into methylene chloride (4 mL) and added dropwise to the solution. After 1 h, methylene chloride (100 mL) was added and the solution was filtered through celite. The filtrate was washed with 1% sodium bisulfite solution (2×10 mL), brine (20 mL), dried over MgSO4 and concentrated to dryness. The residue was purified by silica gel chromatography (ethyl acetate/hexanes 1:1) to give the title compound (225 mg, 58%) as a white solid. 1H NMR (300 MHz, DMSO-d6) δ 7.05-6.95 (m, 1H), 4.04-3.97 (m, 1H), 3.77-3.65 (m, 2H), 2.55-2.50 (m, 1H), 2.38-2.27 (m, 1H), 1.39 (s, 9H), 1.36 (s, 9H). added dropwise to the solution the solution was filtered through celite The filtrate was washed with 1% sodium bisulfite solution (2×10 mL), brine (20 mL) dried over MgSO4 concentrated to dryness The residue was purified by silica gel chromatography (ethyl acetate/hexanes 1:1)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Sodium borohydride (0.63 g, 16.3 mmol) was dissolved into THF (30 mL) and water (4 mL) and cooled to 0° C. (R)-4-tert-butyl 1-(2,5-dioxopyrrolidin-1-yl) 2-(tert-butoxycarbonylamino)succinate (4.6 g, 11.9 mmol) was dissolved into THF (5 mL) and added dropwise to the solution. After 1 h, saturated ammonium chloride (10 mL) was added and the mixture was extracted with ethyl acetate (4×50 mL), dried over MgSO4 and concentrated. The residue was filtered through silica gel with ethyl acetate/hexanes 1:1. The solvent was removed in vacuo to give the title compound (1.91 g, 59%) as a white foam. 1H NMR (300 MHz, DMSO-d6) δ 6.55-6.52 (m, 1H), 4.74-4.69 (m, 1H), 3.81-3.72 (m, 1H), 3.21-3.14 (m, 1H), 2.50-2.39 (m, 1H), 2.19-2.06 (m, 1H), 1.39 (s, 9H), 1.36 (s, 9H). added dropwise to the solution the mixture was extracted with ethyl acetate (4×50 mL) dried over MgSO4 concentrated The residue was filtered through silica gel with ethyl acetate/hexanes 1:1 The solvent was removed in vacuo