Water → (S)-3-((S)-3-(4-(4-tert-butyl-3-isopropylbenzyloxy)phenyl)-3-(isoxazol-3-yl)propanoyl)-4-benzyloxazolidin-2-one

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Reaction Steps

Cesium carbonate (360 mg, 1.1 mmol) was added to a mixture of 7.5 (40.0 mg, 0.10 mmol) and 26.5 (27.0 mg, 0.12 mmol) in DMF (2.0 mL). The resulting mixture was stirred at room temperature for 19 hours. The mixture was then treated with water (5 mL) and extracted with EtOAc (15 mL). The organic layer was separated, washed twice with brine, dried over MgSO4, and concentrated in vacuo. The crude product was purified by flash chromatography on silica gel (0-30% EtOAc/hexane) to give (S)-3-((S)-3-(4-(4-tert-butyl-3-isopropylbenzyloxy)phenyl)-3-(isoxazol-3-yl)propanoyl)-4-benzyloxazolidin-2-one (18.0 mg, 30%) as a clear oil. The ester (18.0 mg, 0.031 mmol) was treated with THF/H2O (3/1, v/v, 2.0 mL) and hydrogen peroxide (30%, 0.021 mL, 0.19 mmol) and cooled to 0° C. LiOH (2.60 mg, 0.062 mmol) was added. The resulting mixture was stirred at 0° C. for 1 hour. A saturated solution of Na2SO3 was added to the mixture, and the reaction was stirred for 1 hour. The mixture was extracted with EtOAc (10 mL), dried over MgSO4, and concentrated in vacuo. The residue was purified by flash chromatography on silica gel (0-30% EtOAc/hexane) to give 26 (5.80 mg, 44%) as a colorless film. MS ESI (neg.) m/e: 420 (M−H). 1H NMR (500 MHz) (CDCl3) δ 8.28 (1H, s); 7.37-7.34 (2H, m); 7.20-7.17 (3H, m); 6.96-6.94 (2H, d, J=8.2Hz); 6.07 (1H, s); 4.98 (2H, s); 4.56 (1H, dd, J=7.8, 7.4 Hz); 3.64 (1H, m), 2.36 (1H, dd, J=16.8, 7.8 Hz), 2.99 (1H, dd, J=16.8, 7.4Hz), 1.43 (9H, s), 1.26 (6H, d, J=7.1Hz).

Provenance & Evidence