反应详情

温度

80 °C

A solution of thiourea (1.32 g, 17.3 mmol) and sodium ethoxide (21% wt in EtOH, 6.5 mL, 17.3 mmol) in ethanol (45 mL) was stirred at room temperature for 15 min, and then was added to a solution of 1,1-dimethoxy-4-dimethylaminobut-3-en-one (3.0 g, 17.3 mmol) in ethanol (20 mL). The reaction was heated to 80° C. for 16 h, and concentrated to dryness to yield 4-dimethoxymethyl-pyrimidine-2-thiol that was used crude in the methylation step. Methylation: To a solution of 4-dimethoxymethyl-pyrimidine-2-thol (4.3 g, 23.1 mmol) in DMF (55 mL) at 0° C. was added sodium hydride (60% dispersion in mineral oil, 1.4 g, 35.0 mmol). The reaction was stirred for 15 min at 0° C. and iodomethane (1.44 mL, 23.1 mmol) was added. After stirring for 16 h, the reaction was partitioned between ethyl acetate and water and extracted with ethyl acetate (2×). The combined organic extracts were dried with MgSO4, concentrated and purified by column chromatography (15% ethyl acetate/hexane) to yield pure acetal 46 (1.94g, 9.7 mmol, 42% for 2 steps). 1H NMR (chloroform-d1): δ=8.56 (d, 1H, J=5 Hz,), 7.19 (d, 1H, J=5 Hz,), 5.19 (s, 1H), 3.42 (s, 6H), 2.58 (s, 3H). Calculated mass=200.2, [M+H]+=201. HPLC (method C) rt=6.1 min (95.2% @ 210-370 nm).

1. concentrationconcentrated to dryness