反应详情

To a stirred, chilled (+3° C.) solution of 3-dodecyl -5-isoxazole carboxylic acid (24.27 g, 0.08625 mol) and triethylamine (12.0 mL, 0.0861 mol) in dry tetrahydrofuran (600 mL) under nitrogen was added in one portion a chilled (+3° C.) solution of ethyl chloroformate (8.25 mL, 0.0863 mol) in dry tetrahydrofuran (30 mL). A white precipitate formed immediately. The suspension was stirred for 1.25 hours before sodium borohydride (6.54 g, 0.173 mol) was added in portions over 10 minutes. The mixture was stirred for 1.5 hours while warming to room temperature. The mixture was rechilled and carefully quenched with water (350 mL). The organic layer was diluted with dichloromethane. The aqueous layer was washed with THF-CH2Cl2. The organic solutions were combined, dried (Na2SO4), and rotoevaporated. The residue was chromatographed on silica gel (1.5 kg, 70-230 mesh) using petroleum ether-acetone (9:1, 20×1 L) eluent. Fractions 10 to 14 were rotoevaporated from dichloromethane and dried in vacuo to give a white solid; yield 11.1 g (48%); mp 57°-59° C.

1. additionwas added in one portion
2. customA white precipitate formed immediately
3. additionwas added in portions over 10 minutes
4. customcarefully quenched with water (350 mL)
5. additionThe organic layer was diluted with dichloromethane
6. washThe aqueous layer was washed with THF-CH2Cl2
7. dry with materialdried (Na2SO4)
8. customThe residue was chromatographed on silica gel (1.5 kg, 70-230 mesh)
9. customdried in vacuo
10. customto give a white solid