反应详情

To a solution of 5-methyl-3H-1,3,4-oxadiazol-2-one (5.509 g, 55.0 mmol) in MeOH (40 mL) is added 25 wt % NaOMe solution in methanol (12.7 mL, 58.8 mmol). The mixture is stirred at rt for 15 min and then concentrated in vacuo. The residue is added to a solution of tetrabutylammonium bromide (0.358 g, 1.08 mmol) and chloro-acetone (4.6 ml, 54.9 mmol) in CHCl3 (33 mL), and the mixture is heated to reflux for 5 h under N2. The mixture is cooled to rt and stirred overnight. The resulting slurry is filtered, and the filtrate is concentrated in vacuo. The residue is purified on a pad of silica gel, eluting with 2:1:1/heptane:EtOAc:DCM to afford 5-methyl-3-(2-oxo-propyl)-3H-1,3,4-oxadiazol-2-one (7.32 g, 86%) as a crystalline solid. MS: 157 (M+H); 1H NMR (300 MHz, CDCl3) δ 4.46 (s, 2H), 2.27 (s, 3H), 2.21 (s, 3H).

1. concentrationconcentrated in vacuo
2. temperaturethe mixture is heated
3. temperatureto reflux for 5 h under N2
4. temperatureThe mixture is cooled to rt
5. stirringstirred overnight
6. filtrationThe resulting slurry is filtered
7. concentrationthe filtrate is concentrated in vacuo
8. customThe residue is purified on a pad of silica gel
9. washeluting with 2:1:1/heptane