Potassium Carbonate → Cilostazol

Participants

Reaction Conditions

Reaction Steps

Into a reaction vessel having a capacity of 500 mL were introduced 6-hydroxy-3,4-dihydrocarbostyril (30 g, 0.18 mol), 1-cyclohexyl-5-(4-chlorobutyl)-1,2,3,4-tetrazole (49.1 g, 0.20 mol, 1.1 M), potassium carbonate (83.84 g, 0.61 mol, 3.3 M), sodium sulfite (1.5 g, 0.01 mol) and purified water (150 mL). The mixture of the reactants was heated at about 85° C. for about 6 hours with circulating by continuous disperser (pipeline homomixer T.K.ROBO MIX manufactured by TOKUSHUKIKA KOGYO CO. LTD.). 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 having a capacity of 1 L and purified water (300 mL) was added thereto, then the crystals were washed with stirring at about 85° C. for about 15 minutes. After washing the crystals, 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 (210 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 (60 mL), then dried at about 80° C. Thus, 62.79 g of cilostazol was obtained. Yield: 92.44%, Purity: 99.61%, m.p.: 158–159° C.

Provenance & Evidence