[CH3:1][O:2][C:3]1[CH:4]=[C:5]([CH:11]([CH:14]=O)[CH:12]=[O:13])[CH:6]=[CH:7][C:8]=1[O:9][CH3:10].[C:16]([NH2:24])(=[NH:23])[C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1>>[CH3:1][O:2][C:3]1[CH:4]=[C:5]([C:11]2[C:12](=[O:13])[NH:24][C:16]([C:17]3[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=3)=[N:23][CH:14]=2)[CH:6]=[CH:7][C:8]=1[O:9][CH3:10](3,4-Dimethoxyphenyl)malonaldehyde acid methyl ester (7.2 g) (30 mmol) and 10 g (42 mmol) of benzamidine are melted at 100° C. The reaction mixture is chromatographed on 250 g of silica gel (0.063-0.2 mm) and the product is eluted with dichloromethane/methanol (9:1 v/v). The eluate is concentrated in a vacuum at 45° C. and the crystalline product is filtered off under suction. The whole is washed with diethyl ether and dried in a high vacuum at room temperature. There are obtained 6.2 g of 5-(3,4-dimethoxyphenyl)-2-phenyl-6(1H)-pyrimidinone as yellow crystals of m.p. 230° C.
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