Reaction Steps
p-Nitrobenzoyl chloride (20.8 g, 0.112 mol) was added at 3–10° C. to a 0° C. to 5° C. solution of (2R, 3R)-3-benzyloxycarbonylamino-4-phenylthio-1,2-butanediol 14 (39.0 g) and triethylamine (39.1 ml, 0.280 mol) in tetrahydrofuran (300 ml). The resulting mixture was stirred for one hour with ice-cooling. Methanesulfonyl chloride (10.4 ml, 0.135 mol) was added dropwise at 2–12° C. and the mixture was stirred with ice-cooling for one hour. Any insoluble matter was filtered off and washed with ethyl acetate. The filtrate and the washing were combined and concentrated under vacuum. The resulting residue was dissolved in ethyl acetate (300 ml) and washed successively with water (50 ml), a 0.5 M aqueous citric acid solution (50 ml), a saturated aqueous solution of sodium hydrogencarbonate (50 ml) and saturated brine (50 ml), dried over magnesium sulfate and concentrated under vacuum. The resulting residue was recrystallized from toluene (400 ml)/diisopropyl ether (300 ml) to give (2R, 3R)-3-benzyloxycarbonylamino-4-phenylthio-2-methanesulfonyloxy-1-(4-nitrobenzyloxy)butane (38.6 g, 51% yield from (2R, 3R)-3-benzyloxycarbonylamino-4-phenylthio-1,2-butanediol 14) as colorless crystals. 1H NMR (CDCl3, 300 MHz) δ 8.5–8.0 (m, 4H), 7.5–7.2 (m, 10H), 5.44 (ddd, J=6.9, 5.1, 2.3 Hz, 1H), 5.11 (s, 2H), 5.09 (brd d, 1H), 4.57 (dd, J=12.0, 6.9 Hz, 1H), 4.50 (dd, J=12.0, 5.1 Hz, 1H), 4.21 (m, 1H), 3.25 (dd, J=14.0, 6.2 Hz, 1H), 3.05 (s, 3H), 3.05 (dd, J=14.0, 8.2 Hz, 1H) IR (KBr): 3347, 1725, 1699, 1531, 1514, 1349, 1283, 1172, 1109, 1028, 925 cm−1, [α]D25: −14.0° (cl.01,CHCl3); Elemental Analysis (C26H26N2O9S2): Calculated: C, 54.35; H, 4.56; N, 4.88; Found: C, 54.49; H, 4.19; N, 4.75.
