Hydrochloric Acid → 7-(4-Propoxyphenyl)-1,1-dioxo-2,3-dihydro-1-benzothiepine-4-carboxylic acid

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Reaction Conditions

Reaction Steps

Ethyl 7-(4-propoxyphenyl)-1,1-dioxo-2,3-dihydro-1-benzothiepine-4-carboxlate (1.0 g, 2.497 mmol) was dissolved in 15 ml of a mixed solution of tetrahydrofuran/ethylene glycol =2/1. Crystals were formed by adding 8.5 ml of water. Potassium carbonate (690 mg, 4.994 mmol) was added and the mixture was heated under reflux for 3.25 hours. Under reflux, 3.5 ml of a 3N hydrochloric acid was dropped to form crystals. After cooling, the mixture was stirred at 20-30° C. for 45minutes and for 1 hour while cooling in ice. After filtration, the residue was washed with 10 ml of a mixed solution of tetrahydrofuran/methanol/water=1/1/3. After vacuum drying (40° C.), 858 mg (Yield 92%) of 7-(4-propoxyphenyl)-1, 1-dioxo-2,3-dihydro-1-benzothiepine-4-carboxylic acid was obtained as pale yellowish white crystals.

Provenance & Evidence