反应详情

To a solution of tert-butyl 4-(bromomethyl)-3,3-difluoro-2-oxopyrrolidine-1-carboxylate (50.1 g) in tetrahydrofuran (400 mL) was added dropwise 1,8-diazabicyclo[5.4.0]undec-7-ene (25.0 mL) at 0° C. over 15 min. After the completion of the dropwise addition, the mixture was stirred at room temperature for 1 hr. Insoluble materials were filtered off and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane:ethyl acetate=4:1). The obtained crystals were washed with diisopropyl ether to give the title compound as colorless crystals (yield 28.1 g, 76%).

1. additionAfter the completion of the dropwise addition
2. filtrationInsoluble materials were filtered off
3. concentrationthe filtrate was concentrated under reduced pressure
4. customThe residue was purified by silica gel column chromatography (eluent: hexane:ethyl acetate=4:1)
5. washThe obtained crystals were washed with diisopropyl ether