反应详情

N-Bromosuccinimide (6.408 g) was added to a solution of 2,2-dimethyl-2H-1-benzopyran-6-carbonitrile (5.55 g) and N-benzyloxycarbonyl-L-alanine (6.69 g) in chloroform (60 ml). After being stirred under reflux for 16 hours, the mixture was poured into saturated aqueous sodium bicarbonate and diluted with chloroform. The organic layer was separated, washed successively with 5% aqueous sodium thiosulfate, water, and brine, dried over magnesium sulfate, and evaporated in vacuo. The oily residue was dissolved in diisopropyl ether and allowed to stand at ambient temperature. The resulting precipitates were collected by filtration, washed with diisopropyl ether, and dried to give (3R,4S)-4-{(2S)-2-benzyloxycarbonylaminopropionyloxy}-3-bromo-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile (4.26 g).

1. temperatureunder reflux for 16 hours
2. customThe organic layer was separated
3. washwashed successively with 5% aqueous sodium thiosulfate, water, and brine
4. dry with materialdried over magnesium sulfate
5. customevaporated in vacuo
6. dissolutionThe oily residue was dissolved in diisopropyl ether
7. customto stand at ambient temperature
8. customThe resulting precipitates
9. filtrationwere collected by filtration
10. washwashed with diisopropyl ether
11. customdried