7-(3-(Benzylamino)propyl)-3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione → 4-Hydroxy-2-methylindole

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Reaction Steps

24.8 g of 7-(3-benzylaminopropyl)-theophylline are heated with stirring for 3 hours to 130° C. with crude 2-methyl-4-(2,3-epoxypropoxy)-indole obtained from 5.9 g of 2-methyl-4-hydroxy indole. Following the addition of chloroform and water, stirring is continued, the layers are separated, the chloroform phase is extracted by shaking twice with water, the chloroform extract is dried with sodium sulphate and the solvent is distilled off. The hydrochloride is precipitated from the alcoholic solution of the residue by acidification with alcoholic hydrochloric acid. The salt recrystallised from ethanol is hydrogenated in alcoholic solution at 60° C./6 atmospheres in the presence of 0.5 g of 5% palladium-carbon catalyst. The filtered reaction solution is concentrated by evaporation in vacuo, the residue is taken up in water and the base described in Example 29 is precipitated with 1N NaOH. Yield: 1.8 g; Melting point: 168°-170° C.

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