2-Aminophenol → 5-(Benzoxazol-2-yl)-2-methyl-1-(tetrahydropyran-4-yl)benzimidazole methanesulfonate

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Reaction Conditions

Reaction Steps

2-methyl-1-(tetrahydropyran-4-yl)benzimidazole-5-carboxylic acid HCl salt (see Working Example 4-3) (51.2 g, 0.19 mol), 2-aminophenol (24.0 g, 0.21 mol), anhydrous DMF (500 mL) and WSC (45.0 g, 0.23 mol) was stirred for 3 hours under an argon atmosphere. Water (2 L) was added, the solid obtained was filtered off, washed with water, After drying at reduced pressure at 50° C., an obtained solid (45.2 gm 0.13 mol) was dissolved in dioxane (500 mL). Methanesulfonic acid (62.5 g, 0.65 mol) was added thereto and this was stirred at 90° C. for 8 hours. The solvent was concentrated at reduced pressure, water (1 L) was added, and the pH was adjusted to 4 with 1N NaOH. Chloroform (2 L) was added for extraction, and then the aqueous layer was extracted with chloroform (1 L), these were combined and the organic layer was washed with brine (1 L). After MgSO4 drying and filtration, the solvent was concentrated under reduced pressure. The residue obtained was dissolved in chloroform (100 mL) and ethyl acetate (150 mL) and methanesulfonic acid (25.0 g) was added. After stirring awhile in the cold, the precipitated solid was filtered off and this was dried under reduced pressure at 50° C. to yield the title compound (23.7 g, 28.1% yield) as a light purple solid.

Provenance & Evidence