反应详情

A solution of NaOMe (0.104 M, 0.8 mL) was added to a solution of 4j (See FIG. 7) (778 mg, 1.71 mmol) in MeOH (10 mL) under N2. After 4 hours, the reaction solution was passed through a Dowex 50W(H+) plug (3×1 cm, eluant MeOH) and the solvent removed to give 2-bromoethyl β-D-galactopyranoside (4e) (See FIG. 7) (450 mg, 92%) (The synthesis of unstable 4e has been described previously. Dahmén et al., “2-Bromoethyl Glycosides .4.2-Bromoethyl Glycosides in Glycoside Synthesis—Preparation of Glycoproteins Containing Alpha-L-Fuc-(1−>2)-D-Gal and Beta-D-Gal-(1>4)-D-Glcnac,” Carbohydr. Res., 125:237-245 (1984), which is hereby incorporated by reference) as a white solid which was used directly in the next step. NaSSO2CH3 (180 mg, 1.34 mmol) was added to a solution 4e (See FIG. 7) (290 mg, 1.01 mmol) in DMF (12 mL) under N2 and warmed to 50° C. After 15 hours, the solution was cooled and the solvent removed. The residue was purified by flash chromatography (MeOH:EtOAc, 1:9) to give 1e (See FIG. 7) (229 mg, 71%) as a white foam; [α]27D=+2.9 (c 0.58, H2O); IR (film) 3358 cm−1 (br, O—H), 1306, 1120 cm−1 (S—SO2); 1H NMR (500 MHz, D2O, COSY) δ 3.29-3.33 (m, 2H, —CH2S—), 3.30 (dd, J1,2 7.7 Hz, J2,3 10.0 Hz, 1H, H-2), 3.35 (s, 3H, CH3SO2—), 3.43 (dd, J2,3 10.0 Hz, J3 4 3.6 Hz, 1H, H-3), 3.48 (ddd, J4,5 0.9Hz, J5,6 4.3 Hz, J5,6′ 7.9 Hz, 1H, H-5), 3.52 (dd, J5,6 4.3 Hz, J6,6 11.7 Hz, 1H, H-6), 3.57 (dd, J5,6′ 7.9 Hz, J6,6 11.7 Hz, 1H, H-6′), 3.70 (dd, 3,4 3.6 Hz, J4,5 0.9 Hz, 1H, H-4), 3.80 (dt, Jd 11.2 Hz, Jt 6.1 Hz, 1H, —OCHH′—), 4.01 (dt, Jd 11.4 Hz, Jt 5.8 Hz, 1H, —OCHH′—), 4.24 (d, J1,2 7.7 Hz, 1H, H-1); 13C NMR (100 MHz, D2O) δ 36.7 (—CH2S—), 50.8 (CH3SO2—), 61.9 (—OCH2—), 69.2, 69.6, 71.7, 73.7, 76.2 (C-2, C-3, C-4, C-5, C-6), 104.0 (C-1); HRMS m/z (FAB+): Found 319.0523 (M+H+); C9H19O8S2 requires 319.0521.

1. customthe solvent removed