Ethyl chloroformate → HCID 135621737, compound

Participants

Reaction Steps

Triphosgene (1.83 g) was dissolved in methylene chloride (20 mL), a solution (30 mL) of a mixture (1:1, 5.57 g) of 5-amino-3-(1-ethoxycarbonylpiperidin-4-yl)-4-phenylisoxazole and 5-amino-3-(1-methoxycarbonylpiperidin-4-yl)-4-phenylisoxazole, and pyridine (3.50 g) in methylene chloride was added dropwise under ice-cooling. After the completion of the dropwise addition, the mixture was stirred under ice-cooling for 20 min, and then at room temperature for 6.5 hrs. The reaction mixture was ice-cooled, aluminum chloride (16.7 g) was added, and the mixture was stirred overnight at room temperature. After the completion of the reaction, the reaction mixture was poured into ice-water, and potassium carbonate was added to alkalify the reaction mixture. An excess amount of ethyl chloroformate was added to the reaction mixture, and the mixture was stirred at room temperature. The insoluble material was filtered off through celite, and the aqueous layer was extracted with chloroform. The organic layer was dried over magnesium sulfate, and the solvent was evaporated under reduced pressure. The precipitated crystals were collected by filtration with diethyl ether and a small amount of methanol to give a mixture (1:1, 2.74 g) of 1-(1-ethoxycarbonylpiperidin-4-yl)-isoxazolo[5,4-c]isoquinolin-5(4H)-one and 1-(1-methoxycarbonylpiperidin-4-yl)-isoxazolo[5,4-c]isoquinolin-5(4H)-one as colorless crystals.

Provenance & Evidence