反应详情

Potassium tert.-butoxide (539 mg., 4.8 mmoles) was dissolved in ethanol (2.12 g., 2.65 ml., 4.6 moles). Diethyl carbonate (625 mg., 5.3 mmoles) and then 2-(5-chloro-2-methoxyphenyl)-2-hydroxyacetamide (1.0 g., 4.6 mmoles) were added and the mixture was stirred for a few minutes to achieve solution, and then heated to reflux for 16 hours, at which time tlc (1:1 ethyl acetate:chloroform) indicated some unreacted starting material. Addition of more diethyl carbonate (625 mg.) and potassium tert-butoxide (100 mg.) and a further 2.5 hours of reflux did not appear to significantly reduce the level of starting acetamide. The reaction mixture was cooled to room temperature, poured into excess, iced 1 N hydrochloric acid and extracted with three portions of chloroform. The combined chloroform extracts were extracted with excess 5% sodium bicarbonate in two portions. The combined bicarbonate extracts were poured slowly into excess 1 N hydrochloric acid to precipitate 5-(5-chloro-2-methoxyphenyl)oxazolidine-2,4-dione (430 mg. 39%; m.p. 179°-181° C.).

1. temperatureheated
2. temperaturea further 2.5 hours of reflux
3. extractionextracted with three portions of chloroform
4. extractionThe combined chloroform extracts were extracted with excess 5% sodium bicarbonate in two portions
5. additionThe combined bicarbonate extracts were poured slowly into excess 1 N hydrochloric acid
6. customto precipitate 5-(5-chloro-2-methoxyphenyl)oxazolidine-2,4-dione (430 mg. 39%; m.p. 179°-181° C.)