C=O.[C:3]([BH3-])#[N:4].[Na+].[O:7]=[C:8]1[NH:13][C:12]([C:14]2[CH:19]=[C:18](N)[CH:17]=[CH:16][C:15]=2[O:21][CH2:22][CH3:23])=[N:11][CH:10]=[C:9]1[C:24]([O:26]CC)=[O:25].[C:29](O)(=O)C>O.C(#N)C.C(OCC)C>[O:7]=[C:8]1[NH:13][C:12]([C:14]2[CH:19]=[C:18]([N:4]([CH3:3])[CH3:29])[CH:17]=[CH:16][C:15]=2[O:21][CH2:22][CH3:23])=[N:11][CH:10]=[C:9]1[C:24]([OH:26])=[O:25]
A solution (1.9 ml.) of 37% formaldehyde (23.8 mmoles) in water followed by sodium cyanoborohydride (450 mg., 7.15 mmoles) were added to a stirred solution of ethyl 1,6-dihydro-6-oxo-2-(5-amino-2-ethoxyphenyl)pyrimidine-5-carboxylate (720 mg., 2.38 mmoles) in acetonitrile (14 ml.). Glacial acetic acid (0.24 ml.) was then added over a period of one minute. The mixture was stirred at room temperature for 2 hours. Additional glacial acetic acid (0.24 ml.) was added and stirring was continued for an extra 0.5 hour. The mixture was treated with diethyl ether (35 ml.). The organic layer was washed with 10% aqueous sodium bicarbonate (3 × 10 ml.) followed by brine (30 ml.) and dried (sodium sulfate). The solvent was removed and a solution of the residue in acetonitrile-diethyl ether was extracted with 1 N sodium hydroxide (3 × 20 ml.). The aqueous extract was acidified with glacial acetic acid to pH 6. The precipitate was collected and recrystallized from acetonitrile to give the title compound (210 mg., 29%), m.p. 187°-196°. Recrystallization from benzene-Skellysolve B gave analytical material, m.p. 195°-198°.
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