反应详情

温度

-78 °C

Ethoxycarbonylmethylene triphenyl phosphorane (33.8 g) in dry THF (200 ml) was treated with isopropyl isothiocyanate (10.1 g) at 65° C. for 16 h under nitrogen. The mixture was cooled to −78° C. and methyl 3-bromo-2-oxo-butanoate was added. The reaction was allowed to warm slowly to room temperature. After 24 h at room temperature more methyl 3-bromo-2-oxo-butanoate (2.8 g) was added and the mixture was warmed to 60° C. for 16 h. The cooled reaction was poured into water (1.5 L) and extracted into ether. Drying and evaporation gave an oil which was chromatographed (SiO2/10:1 isohexane-ethyl acetate then 5:1 isohexane-ethyl acetate) to afford the subtitle compound (23.5 g). δ 1HCDCl3 1.23-1.35 (9H, m), 2.26 (3H,s), 3.46 (1H, m), 3.82 (3H, s), 4.2 (2H, q), 7.42 (1H, br.s)

1. temperatureto warm slowly to room temperature
2. temperaturethe mixture was warmed to 60° C. for 16 h
3. customThe cooled reaction
4. extractionextracted into ether
5. customDrying
6. customevaporation
7. customgave an oil which
8. customwas chromatographed (SiO2/10:1 isohexane-ethyl acetate