Trimethyl orthoformate → 1H-Benzimidazole-5-carboxylic acid, 7-iodo-, methyl ester

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Reaction Steps

To a solution of 3,4-diamino-5-iodo-benzoic acid methyl ester (1.68 g, 5.75 mmol) in THF (20 mL) was added trimethyl orthoformate (1.26 mL, 11.5 mmol) and 4-toluenesulfonic acid (11 mg, 0.057 mmol). The mixture was stirred at room temperature overnight, then partitioned between ethyl acetate and water. The organic layer was separated, dried over MgSO4, filtered and concentrated under reduced pressure to give 783 mg (45%) of 7-Iodo-3H-benzoimidazole-5-carboxylic acid methyl ester, MS (M+H)=303.

Provenance & Evidence