1-Hydroxybenzotriazole → 1-[[(3-Ethoxy-2-thienyl)carbonyl]amino]cyclohexanecarboxylic acid

Participants

Reaction Steps

633 mg (3.3 mmol) of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added to a solution of 581 mg (3 mmol) of 1-aminocyclohexanecarboxylic acid methyl ester hydrochloride, 482 mg (3.1 mmol) of 1-hydroxybenzotriazole, 517 mg (3 mmol) of 3-ethoxy-2-thiophenecarboxylic acid and 1.16 g (9 mmol) of diisopropylethylamine in 10 ml of methylene chloride under ice-cooling. After the mixture was stirred at room temperature overnight, the reaction solution was concentrated under reduced pressure, ethyl acetate was added thereto, and the mixture was washed with water, a 10% aqueous potassium hydrogensulfate solution, a saturated aqueous sodium hydrogencarbonate solution and then saturated brine, followed by drying with anhydrous sodium sulfate. After the solvent was distilled off under reduced pressure, diisopropyl ether was added to the residue, the mixture was stirred overnight, and the crystal was collected by filtration. Then, the obtained crystal was dissolved in 3 ml of tetrahydrofuran solution, 2.8 ml of 2N aqueous NaOH solution was added thereto, and the mixture was heated under reflux for 3 hours. Ether was added to the reaction solution and the aqueous layer was separated. After the separated aqueous layer was neutralized by concentrated hydrochloric acid, it was extracted with ethyl acetate. After the obtained organic layer was washed with saturated brine, it was dried with anhydrous sodium sulfate. The solvent was distilled off under reduced pressure to obtain 656 mg (73%) of the title compound.

Provenance & Evidence