Water → (2R,3S)-3-acetamido-N-tert-butyl-2-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl)tetrahydrofuran-3-carboxamide

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A solution of (2R,3S)-3-acetamido-2-allyl-N-tert-butyltetrahydrofuran-3-carboxamide (930 mg, 3.47 mmol) in dichloromethane (20 mL), was treated with chloro-1,5-cyclooctadiene iridium(I) dimer (70 mg, 3 mol %) and 1,2-bis(diphenylphosphino)-ethane (83 mg, 6 mol %). The solution was stirred at room temperature for 30 minutes and then 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (1.01 mL, 6.94 mmol) was added dropwise, and the reaction was stirred overnight at room temperature. The next day, the reaction mixture was poured into water and the aqueous solution was extracted using ethyl acetate (3×). The combined organic layers were washed with saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate, filtered and concentrated. Purification by flash column chromatography (silica gel, 50-80% ethyl acetate in dichloromethane) gave (2R,3S)-3-acetamido-N-tert-butyl-2-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl)tetrahydrofuran-3-carboxamide as a colorless oil (864 mg, 63%). 1H NMR (CDCl3, 300 MHz) δ 7.01 (s, NH, 1 H), 6.10 (s, NH, 1 H), 4.38 (m, 1 H), 4.12 (m, 1 H), 4.00 (m, 1 H), 2.96 (m, 1 H), 2.02-2.18 (m, 2 H), 1.99 (s, 3 H), 1.42-1.62 (m, 3 H), 1.36 (s, 9 H), 1.22 (s, 12 H), 0.76 (m, 2 H); MS (+CI): m/z for C20H37BN2O5: expected 396.3; found 397.4 (M+H)+.

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