反应详情

To a solution of (1R,3aS,5aR,5bR,7aR,11aR,11bR,13aR,13bR)-3a-((tert-butoxycarbonyl)amino)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl trifluoromethanesulfonate (0.2 g, 0.304 mmol) in dichloromethane (2 mL) was added trifluoroacetic acid (0.5 mL, 6.49 mmol). The mixture was stirred at rt for 1.5 h then was concentrated under reduced pressure. The residue was diluted with saturated aqueous sodium bicarbonate (20 mL) and was extracted with dichloromethane (3×20 mL). The combined organic layers were dried with Na2SO4. The drying agent was removed by filtration and the filtrate was concentrated and adsorbed to silica gel then was purified by flash chromatography using a 12-100% ethyl acetate in hexanes gradient and a 12 g Thomson silica gel column. The fractions containing the expected product were combined and were concentrated under reduced pressure to give (1R,3aS,5aR,5bR,7aR,11aR,11bR,13aR,13bR)-3a-amino-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl trifluoromethanesulfonate (0.109 g, 0.195 mmol, 64.3% yield) as an off-white solid. 1H NMR (500 MHz, chloroform-d) δ=5.57 (dd, J=6.8, 1.9 Hz, 1H), 4.73 (d, J=1.6 Hz, 1H), 4.63-4.60 (m, 1H), 2.54 (td, J=10.9, 5.3 Hz, 1H), 2.17 (dd, J=17.1, 6.9 Hz, 1H), 2.08-1.99 (m, 1H), 1.70 (s, 3H), 1.13 (s, 3H), 1.08 (s, 3H), 1.03 (s, 3H), 0.97 (s, 3H), 0.93 (s, 3H), 1.82-0.91 (m, 20H).

1. concentrationthen was concentrated under reduced pressure
2. additionThe residue was diluted with saturated aqueous sodium bicarbonate (20 mL)
3. extractionwas extracted with dichloromethane (3×20 mL)
4. dry with materialThe combined organic layers were dried with Na2SO4
5. customThe drying agent was removed by filtration
6. concentrationthe filtrate was concentrated
7. customthen was purified by flash chromatography
8. additionThe fractions containing the expected product
9. concentrationwere concentrated under reduced pressure