[Synthesis]
((2R,3R)-3-(Benzoyloxy)-4,4-difluoro-5-hydroxytetrahydrofuran-2-yl)methyl benzoate (4.14 g, 10.9 mmol) was dissolved in anhydrous dichloromethane (52 mL), anhydrous triethylamine (2.4 mL) was added, and the solution was cooled to 0 °C. Methylsulfonyl chloride (1.23 mL, 15.8 mmol) was added slowly and dropwise with stirring. The reaction mixture was stirred at room temperature for 18 hours. After completion of the reaction, the mixture was diluted with dichloromethane (140 mL) and washed with saturated sodium bicarbonate solution (56 mL). The organic phase was dried with anhydrous sodium sulfate and concentrated under reduced pressure to give an oily product as a mixture of isomers (5.03 g, quantitative yield).
19F NMR (CDCl3, 471 MHz): δ -107.70, -108.22, -120.65, -121.17, -122.21, -122.73, -123.76, -124.45.
1H NMR (CDCl3, 500 MHz) of the major isomer (60%): δ 8.13-8.04 (m, 4H, Bz), 7.65-7.54 (m, 2H, Bz), 7.50-7.41 (m, 4H, Bz), 6.17 (d, J = 5.6 Hz, 1H, H-1), 5.62 (dd, J1 = 4.2 Hz, J2 = 16.4 Hz), 5.62 (dd, J1 = 16.4 Hz, J2 = 16.4 Hz, J2 = 16.4 Hz). J2 = 16.4 Hz, 1H, H-3), 4.91 (q, J = 3.9 Hz, 1H, H-4), 4.81-4.61 (m, 2H, H-5), 3.17 (s, 3H, CH3).
1H NMR (CDCl3, 500 MHz) of the secondary isomer (40%): δ 8.13-8.04 (m, 4H, Bz), 7.65-7.54 (m, 2H, Bz), 7.50-7.41 (m, 4H, Bz), 6.09 (d, J = 6.4 Hz, 1H, H-1), 5.98 (dt, J1 = 7.3 Hz, J2 = 15.0 Hz, 1H, H-3), 4.81-4.61 (m, 3H, H-4, H-5), 3.03 (s, 3H, CH3).
13C NMR (CDCl3, 126 MHz): δ 40.09, 40.20 (CH3), 62.52, 63.08 (C-5), 69.61 (dd, J1C-F = 15.7 Hz, J2C-F = 26.0 Hz, C-3), 71.04 (dd, J1C-F = 17.4 Hz, J2C-F = 36.4 Hz C-3), 79.68, 79.75, 82.59 (C-4), 98.81 (dd, J1C-F = 25.0 Hz, J2C-F = 41.8 Hz, C-1), 99.52 (dd, J1C-F = 24.5 Hz, J2C-F = 46.3 Hz, C-1), 120.61 (dd, J1C-F = 253.5 Hz, J2C-F = 269.8 Hz, C-2), 120.91 (dd, J1C-F = 249.3 Hz, J2C-F = 276.3 Hz, C-2), 128.42, 128.58, 128.63, 128.70, 128.76, 128.79 (Ph), 129.18, 129.25 ('ipso ' Ph), 129.76, 130.07, 130.14, 133.51, 133.63, 134.19, 134.26 (Ph), 164.89, 165.03, 165.81, 165.90 (CO). |