Pyridine-4-amidine hydrochloride → 5-(2-Methoxyphenoxy)-2-(4-pyridyl)-tetrahydropyrimidine-4,6-dion

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To a stirred solution of sodium methylate (9.7 g) in methanol (100 ml) a solution of dimethyl-(2-methoxyphenoxy)malonate (21.7 g) in methanol (50 ml) was added within 15 min and stirring was continued for 30 min followed by the addition of 4-amidino-pyridine hydrochloride (15 g, Referential Example 2) followed by stirring at room temperature for 20 h. The reaction mixture was concentrated in vacuo. The solid residue was stirred with diethyl ether. The obtained powder was filtered off and dissolved in water (300 ml). Acetic acid was added to pH=4. The precipitated product was filtered off, washed with water and dried in vacuo at 500C. 5-(o-methoxyphenoxy)4,6-dihydroxy-2-(4-pyridyl)pyrimidine (20.1 g, possibly also present as the tautomeric 5-(2-methoxyphenoxy)-2-(4-pyridyl)-tetrahydropyrimidine-4,6-dion) was obtained as a white powder.

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