反应详情

Mass spectrum (FAB, Pos):m/z 177 (M30 +1, as a free base). ##STR11## 1-Methylbenzimidazole-5-carboxylic acid hydrochloride, 20.2 g (including inorganic matters), was added to 300 ml of methanol and 5 ml of conc. hydrochloric acid was added to the mixture followed by heating to reflux for 7 hours. The solvent was distilled off and 200 ml of water was added to the residue. At 5° to 10° C., 1 N sodium hydroxide solution was added to the mixture to adjust pH to 9 to 10 followed by extraction with ethyl acetate. The ethyl acetate layer was dried over anhydrous magnesium sulfate and filtered. The solvent was distilled off under reduced pressure. The resulting crystals were washed with ether to give 4.8 g of methyl 1-methyl-benzimidazole-5-carboxylate (43.6%, based on 1,5-dimethylbenzimidazole).

1. additionwas added to the mixture
2. temperatureby heating
3. temperatureto reflux for 7 hours
4. distillationThe solvent was distilled off
5. addition200 ml of water was added to the residue
6. additionAt 5° to 10° C., 1 N sodium hydroxide solution was added to the mixture
7. extractionfollowed by extraction with ethyl acetate
8. dry with materialThe ethyl acetate layer was dried over anhydrous magnesium sulfate
9. filtrationfiltered
10. distillationThe solvent was distilled off under reduced pressure
11. washThe resulting crystals were washed with ether