2-Aminophenol → 2-Acetoxymethyl-5-(2-hydroxyanilinocarbonyl)-1-(tetrahydropyran-4-yl)benzimidazole

Participants

Reaction Conditions

Reaction Steps

A 4-neck flask (200 mL) equipped with a reflux condenser was charged with 2-acetoxymethyl-1-(tetrahydropyran-4-yl)benzimidazole-5-carboxylic acid (see Working Example 7-1) (1.50 g, 4.71 mmol), anhydrous tetrahydrofuran (40 mL), and oxalyl chloride (0.657 g, 5.18 mmol), and anhydrous N,N-dimethylformamide (0.4 mL) was then added dropwise at room temperature, after which the reaction mixture was stirred at 50° C. for 14 hours. After being allowed to cool to room temperature, the solvent was distilled off under reduced pressure to give a pale yellow residue which was cooled to 0 to 5° C., which was taken up in anhydrous tetrahydrofuran (40 mL) and diisopropylamine (0.79 mL, 5.65 mmol), followed by 2-aminophenol (0.57 g, 5.81 mmol), and this was stirred for 24 hours at room temperature. The precipitated crystals were filtered off, these were washed with tetrahydrofuran and dried under reduced pressure with heating to yield the title compound (2.40 g, quant.) as a white powder.

Provenance & Evidence