Hydrochloric Acid → Pirmagrel

Participants

Reaction Steps

5-(5-Ethoxycarbonylpentyl)-imidazo[1,5-a]pyridine (1091 g) is charged into a 12 liter round bottom flask under a nitrogen atmosphere. Ethyl alcohol (95%, 420 ml) is added while stirring. With continued stirring, 2 N NaOH (2100 ml) is added in portions. After complete addition the mixture is warmed at 70° for 20 minutes, at which time a solution is obtained, and heating is continued for 2 hours. Additional sodium hydroxide (50% solution, 21 ml) is added and heating is continued for 40 more minutes. The reaction mixture is cooled, 12 N HCl (30 ml) is added, and the ethyl alcohol is partially removed by evaporation under reduced pressure. The resulting solution is washed with ethyl ether (1700 ml), decolorized with charcoal, filtered, and acidified with acetic acid (300 ml). The product that crystallizes at 4° overnight is collected, washed first with water, then with ethyl ether (1000 ml), and dried to give 5-(5-carboxypentyl)-imidazo[1,5-a]pyridine, melting at 146°-8°, and identical to the product of Example 2.

Provenance & Evidence