Potassium Carbonate → Cilostazol

Participants

Reaction Conditions

Reaction Steps

Into a flask having a capacity of 200 mL were introduced 6-hydroxy-3,4-dihydrocarbostyril (12 g, 0.07 mol), 1-cyclohexyl-5-(4-chlorobutyl)-1,2,3,4-tetrazole (19.64 g, 0.08 mol), potassium carbonate (22.36 g, 0.16 mol), sodium hydroxide (2.35 g, 0.05 mol), sodium sulfite (0.6 g, 0.004 mol) and purified water (60 mL). The mixture of the reactants was heated at about 92° C. for about 6 hours. After the completion of the reaction, the reaction mixture was cooled to around 50° C., and the deposited crude crystals were once collected by filtration. The crystals obtained were introduced into a flask and purified water (120 mL) was added thereto, then the crystals were washed with stirring at about 85° C. for about 15 minutes. The reaction mixture was cooled to around 50° C., and the precipitated crystals were collected by filtration. The crystals obtained were introduced into a flask again and methanol (84 mL) was added thereto, then the crystals were washed with stirring at about 25° C. for about 15 minutes. The reaction mixture was cooled to 10° C. or less, the precipitated crystalline product was collected by filtration and washed with methanol (24 mL), then dried at about 80° C. Thus, 24.15 g of cilostazol was obtained. Yield: 88.88%, Purity: 99.50%, m.p.: 158–159° C.

Provenance & Evidence