反应详情

To a stirred suspension of NaH (35.20 g, 0.88 mol, 60% in mineral oil) in anhydrous THF (1000 mL) was added ethyl formate (88.80 g, 0.90 mol) and the title compound of step 1 (126.0 g, 0.80 mol) in anhydrous THF (100 mL). The mixture was stirred at r.t. for 0.5 hour and refluxed for 3 h. In a separate flask, S-methylthiopseudourea hemisulfate (133.44 g, 0.96 mol) and sodium ethoxide (65.28 g, 0.96 mol) in EtOH (200 mL) were stirred at r.t. for 1 h, whereupon this mixture was added to the above mixture. There combined mixture was refluxed for 15 h, cooled, and the pHwas adjusted to 5 with acetic acid. After concentration under vacuum, silica gel chromatography (DCM: MeOH=50/110/1) gave the title compound (30.00 g, 17.7% yield) as a yellow solid. 1H NMR (CDCl3, 400 MHz) δ 12.08 (s, 1H), 7.49 (s, 1H), 3.83-3.80 (m, 2H), 2.55 (s, 3H), 1.37-1.28 (m, 1H), 0.65-0.62 (m, 2H), 0.37-0.34 (m, 2H).

1. temperaturerefluxed for 3 h
2. additionwhereupon this mixture was added to the above mixture
3. temperaturewas refluxed for 15 h
4. temperaturecooled
5. concentrationAfter concentration under vacuum, silica gel chromatography (DCM: MeOH=50/110/1)