反应详情

n-Butyl lithium (2.5M in hexanes, 22.5 ml) was added dropwise over 40 minutes with stirring to fresh ethyl propiolate (6.0 ml) in dry tetrahydrofuran (75 ml) under nitrogen, with the temperature being maintained below −68° by external cooling. After 30 minutes, isovaleraldehyde (6.5 ml) in dry tetrahydrofuran (15 ml) was added over 15 minutes with the temperature maintained below −69°. After one hour, trimethylsilyl chloride (10 ml) was added and the reaction was allowed to warm to room temperature. Water was added and the mixture was extracted with ethyl acetate, which was washed with brine, dried, and evaporated to give ethyl 4hydroxy-6-methyl-2-heptynoate as an oil (9.5 g).

1. temperaturebeing maintained below −68° by external cooling
2. temperaturemaintained below −69°
3. waitAfter one hour
4. extractionthe mixture was extracted with ethyl acetate, which
5. washwas washed with brine
6. customdried
7. customevaporated