90% |
With copper(ll) sulfate pentahydrate; sodium L-ascorbate; In water; N,N-dimethyl-formamide; at 20.0℃; for 14.0h;Inert atmosphere; |
(+)-((2R,3R,4S,5R,6S)-3-Acetoxy-6-(((3R,4R,5S)-5-azido-4-hydroxytetrahydro- 2//-pyran-3-yl)thio)-5-methoxy-4-(4-(3,4,5-trifluorophenyl)-li/-l,2,3-triazol-l- yl)tetrahydro-2 /-pyran-2-yl)methyl acetate (62 mg, 0.101 rnmol) and <strong>[153800-11-4]2-ethynylpyrazine</strong> (16.75 mg, 0.161 mmol) were dissolved in a previously degassed solution of DMF (3 mL) and water (1.000 ml) and the mixture was placed under argon. Sodium ascorbate (23.90 mg, 0.121 mmol) and copper(II) sulfate pentahydrate (35.2 mg, 0.141 mmol) (predissolved in 0.5 rnL water) were added and the reaction mixture was stirred at room temperature for 14 h. The mixture and the solid clinging to the stir bar were dissolved by the addition of dichloromethane and methanol. Water (10 mL) and saturated aqueous sodium bicarbonate (10 mL) were added resulting in the formation of a precipitate. The mixture was filtered through a pad of Celite and the filter cake was rinsed with 5% methanol in dichoromethane. The filtrate was transferred to a separatory funnel . Brine (1(3 mL) was added and the aqueous layer was extracted (with gentle shaking) with 5% methanol in dichloromethane (4 x 15 mL). The combined organic layers were washed with brine (15 mL). The organic layer was dried over MgS04, filtered, and concentrated. The product was purified by column chromatography on silica gel (30% ethyl acetate containing 5% methanol/ hexanes 100% ethyl acetate containing 5% methanol/hexanes; 24 g column) to afford ((2R,3R,4S,5R,6S)-3-acetoxy-6-(((3R,4R,5S)-4-hydroxy-5-(4-(pyrazin-2-yl)-l /7-l ,2,3-triazol-l-yl)tetrahydro-2i7-pyran-3-yl)thio)-5- methoxy-4-(4~(3,4,5-trifluorophenyl)-li/-L2,3~triazoi-l-yl)tetrahydro-2/f-pyran~2- yl)m ethyl acetate (65 mg, (3 09(3 mmol, 90% yield) as a white solid. 41 NMR (4(30 MHz, CHLOROFORMS) d 9.44 (d, 7=0.8 Hz, 1H), 8.55 (s, 2H), 8.35 (s, 1H), 7.83 (s, 1H), 7.47 (dd, .7=8.0, 6 5 Hz, 2H), 5.51 (d, 7=2.8 Hz, H I ), 4.74 - 4.64 (m, 2H), 4 62 - 4 52 (m, 1H), 4.40 (dd, 7=11.5, 5.0 Hz, 1H), 4.32 (dd, 7=11.8, 5.0 Hz, 1 1 1). 4.26 (t, 7=9.9 Hz, 1H), 4.20 - 4.09 (m, 4H), 4 09 - 4 03 (m, 1 H), 3.52 (t, 7=1 1.9 Hz, 1H), 3 36 (s, 3H), 3 17 (ddd. 7=1 1 .8, 9.8, 5.0 Hz, i l l ), 2.1(3 (s, 31 1 ), 1.94 (s, 3H); 1.C7MS (ESI) mie 721 .2 [(M+H)+, calcd for CsoHxrFsNsOgS 721.2], /R = 1.88 min (Method 2). |