反应详情

Compound 22 (5 g) was dissolved a 1:1 mixture of benzene and triethylorthoacetate (110 mL), containing 4-toluenesulfonic acid (0.2 g), and the mixture was stirred for 1 h at room temperature. The acid was neutralized with triethylamine, and the mixture evaporated to dryness. The residue was dissolved in 80% aqueous acetic acid (75 mL) and stirred for 40 min at room temperature. The acetic acid was evaporated under diminished pressure and the last traces were removed by co-evaporation with toluene to yield 23 (4.7 g, 91.3%); [α]D, -4.5° (c 0.8, chloroform), t.l.c. (5:1 ethyl acetate-toluene). 13C NMR (CDCl3): δ170.98 (COCH3), 166.75, 166.33, 166.18, 165.07 (4×PhCO), 102.03, 101.08 (C-1, C-1'), 98.16 (C-1 fuc), 80.07, 78.23 (C-3, C-4), 74.69, 73.53, 73.24 (3×PhCH2), 70.66 [OCH2 (CH2)6 ], 63.23, 61.42 (C-6, C-6'), 32.25-23.14 [(CH2)6CH3 ], 21.20 (COCH3), 17.49 (C-6 fuc), and 14.63 (CH3).

1. customthe mixture evaporated to dryness
2. dissolutionThe residue was dissolved in 80% aqueous acetic acid (75 mL)
3. stirringstirred for 40 min at room temperature
4. customThe acetic acid was evaporated under diminished pressure
5. customthe last traces were removed by co-evaporation with toluene