反应详情

5-(4-Acetoxyphenyl)-2-acetylamino-3-benzylpyrazine (c-33) (355 mg, 982 μmol) was dissolved in methanol (8 mL), to which was added 10% (w/v) aqueous solution of sodium hydroxide (1.8 mL) while stirring at room temperature and then stirred for an hour. To this was added 2 M hydrochloric acid to stop the reaction and extracted 3 times with ethyl acetate. The organic layer was washed with saturated brine and then dried over anhydrous sodium sulfate. After removing anhydrous sodium sulfate by filtration, the filtrate was concentrated under reduced pressure. After purifying the residue by column chromatography (37 g, n-hexane/ethyl acetate=1/2), the obtained solid was recrystallized from methanol to give 2-acetylamino-3-benzyl-5-(4-hydroxyphenyl)pyrazine (coelenteracetamide) (c-25) as a colorless solid (109 mg, 34.8%). Rf=0.23 (n-hexane/ethyl acetate=1/2). UV (MeOH) λmax (log ε) 332 (4.14), 294 (4.15), 275.5 (4.12). UV (pH 7.4 PB) λmax (log ε) 328 (4.14), 289.5 (4.03), 270 (4.08). 1H NMR (400 MHz, DMSO-d6) δ 2.03 (s, 3H), 4.13 (s, 2H), 6.84-6.89 (AA′BB′, 2H), 7.14-7.21 (m, 3H), 7.23-7.29 (m, 2H), 7.89-7.94 (AA′BB′, 2H), 8.80 (s, 1H), 9.91 (s, 1H), 10.21 (s, 1H). IR (KBr, cm−1) 592, 631, 702, 746, 837, 1128, 1157, 1173, 1211, 1231, 1279, 1314, 1368, 1435, 1497, 1518, 1543, 1582, 1591, 1611, 1672, 3026, 3073, 3254. HRMS (FAB+) m/z 320.1399 (M+H, C19H18N3O2 requires 320.1399).

1. stirringstirred for an hour
2. customthe reaction
3. extractionextracted 3 times with ethyl acetate
4. washThe organic layer was washed with saturated brine
5. dry with materialdried over anhydrous sodium sulfate
6. customAfter removing anhydrous sodium sulfate
7. filtrationby filtration
8. concentrationthe filtrate was concentrated under reduced pressure
9. customAfter purifying the residue by column chromatography (37 g, n-hexane/ethyl acetate=1/2)
10. customthe obtained solid was recrystallized from methanol