反应详情

To a solution of 45.2 mmol of sodium ethoxide (made in situ from sodium and absolute ethanol) in 40 mL of absolute ethanol was added formamidine hydrochloride (1.74 g, 21.5 mmol) and 2-cyano-4,4-diethoxy-butyric acid ethyl ester (2.47 g, 11 mmol, literature reference: Davoll, J., J. Chem. Soc. 131-138 (1960)). The mixture was refluxed for 6 hours, cooled to room temperature and filtered. The solid was washed with hot acetonitrile. The filtrate was neutralized with acetic acid to pH 6.5 and then evaporated to half of the volume. Ethyl acetate (50 mL) was added to the resultant filtrate. The precipitate was filtered, washed with EtOAc to give 1.6 g (66%) of 6-amino-5-(2,2-diethoxy-ethyl)-3H-pyrimidin-4-one as a white solid which was used without further purification. 1H NMR (300 MHz, DMSO-d6) δ 11.46 (s, br, 1H, NH), 7.68 (s, 1H), 6.07 (s, br, 2H, NH2), 4.54 (t, J=6.0 Hz, 1H, CH(OCH2CH3)2), 3.53-5.62 (m, 2H, CH(OCH2CH3)2), 3.31-3.49 (m, 2H, CH(OCH2CH3)2), 2.50 (m, 2H, CH2), and 1.05 (t, J=6.93 Hz, 6H, CH(OCH2CH3)2).

1. temperatureThe mixture was refluxed for 6 hours
2. filtrationfiltered
3. washThe solid was washed with hot acetonitrile
4. customevaporated to half of the volume
5. additionEthyl acetate (50 mL) was added to the resultant filtrate
6. filtrationThe precipitate was filtered
7. washwashed with EtOAc