反应详情

温度

85 °C

To a sealable vial containing ethyl 3-(tributylstannyl)-1H-pyrazole-5-carboxylate (0.052 g, 0.122 mmol) was added ((1R,3aS,5aR,5bR,7aR,11aR,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-9-(trifluoromethylsulfonyloxy)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-3a-yl)methyl benzoate (0.075 g, 0.111 mmol), lithium chloride (0.014 g, 0.332 mmol), and tetrakis(triphenylphosphine)palladium(0) (6.40 mg, 5.54 μmol). The mixture was diluted with 1,4-Dioxane (2 mL) and was flushed with N2. The vial was sealed and heated to 85° C. for 15.5 h. The mixture was cooled to rt, was diluted with water (4 mL) and was extracted with dichloromethane (3×4 mL). The combined organic layers were dried with Na2SO4. The drying agent was removed by filtration and the filtrate was concentrated under reduced pressure. The residue purified by Biotage flash chromatography using a 0-25% EtOAc in hexanes gradient. The fractions containing the expected product were combined and concentrated under reduced pressure to give ethyl 3-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(benzoyloxymethyl)-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)-1H-pyrazole-5-carboxylate (0.070 g, 0.105 mmol, 95% yield) as a white solid. LCMS: m/e 665.66 (M−H)−, 2.74 min (method 1). 1H NMR (500 MHz, CHLOROFORM-d) δ ppm 0.85-1.84 (m, 21H), 0.91 (s, 3H), 1.02 (s, 3H), 1.03 (br. s., 3H), 1.05 (s, 3H), 1.10 (s, 3H), 1.71 (s, 3H), 1.89-2.07 (m, 3H), 2.15 (dd, J=17.70, 6.41 Hz, 1H), 2.53 (td, J=11.06, 5.95 Hz, 1H), 4.11 (d, J=10.99 Hz, 1H), 4.38 (q, J=7.02 Hz, 2H), 4.52 (d, J=10.07 Hz, 1H), 4.61 (s, 1H), 4.72 (d, J=1.53 Hz, 1H), 5.75 (d, J=4.58 Hz, 1H), 6.73 (s, 1H), 7.44 (t, J=7.78 Hz, 2H), 7.55 (t, J=7.32 Hz, 1H), 8.05 (d, J=7.02 Hz, 2H).

1. customwas flushed with N2
2. customThe vial was sealed
3. temperatureThe mixture was cooled to rt
4. additionwas diluted with water (4 mL)
5. extractionwas extracted with dichloromethane (3×4 mL)
6. dry with materialThe combined organic layers were dried with Na2SO4
7. customThe drying agent was removed by filtration
8. concentrationthe filtrate was concentrated under reduced pressure
9. customThe residue purified by Biotage flash chromatography
10. additionThe fractions containing the expected product
11. concentrationconcentrated under reduced pressure