反应详情

To a suspension of 3-carboxy-1,2,4-thiadiazolo[4,5-a]benzimidazole (10.00 g, 45.62 mmol) in methanol (150 ml) and water (100 ml), 1M NaOH (45.6 ml) was added over a period of 1 h. After 4 h, the solution turned clear and the methanol was removed under reduced pressure. The aqueous solution was extracted with chloroform, the aqueous phase was freeze-dried to give the title compound (10.4 g, 95%) as a white solid: mp 225-227° C.; 1H NMR (DMSO-d6) δ 7.68 (d, 1H), 7.05 (d, 1H), 6.95 (t, 1H), 6.80 (t, 1H) ppm; 13C NMR (DMSO-d6) δ 167.20, 161.76, 149.68, 148.84, 129.52, 126.23, 122.74, 118.37, 116.06 ppm; IR (KBr) ν 3395, 3243, 1663, 1641, 1522, 1443, 1334, 827, 729 cm-1.

1. additionwas added over a period of 1 h
2. customthe methanol was removed under reduced pressure
3. extractionThe aqueous solution was extracted with chloroform
4. customthe aqueous phase was freeze-dried