反応手順
To a sealable vial containing (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 (0.25 g, 0.448 mmol) was added ethyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)cyclohex-3-enecarboxylate (0.138 g, 0.493 mmol), sodium carbonate hydrate (0.167 g, 1.345 mmol), and palladium tetrakis (0.016 g, 0.013 mmol). The mixture was diluted with 1,4-dioxane (4 mL) and water (1 mL) then was flushed with nitrogen and was sealed and heated to 85° C. in an oil bath. After 5 h of heating, the mixture was cooled to rt, diluted with water (20 mL), and extracted with ethyl acetate (3×20 mL). The organic layers were washed with brine, dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography using a 6-50% ethyl acetate in hexanes gradient and 40 g silica gel column. The fractions containing the expected product were combined and concentrated under reduced pressure to give ethyl 4-((1R,3 aS,5aR,5bR,7aR,11aS,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)cyclohex-3-enecarboxylate (0.119 g, 0.212 mmol, 47.3% yield) as an off-white solid. LCMS: m/e 562.6 (M+H)+, 2.13 min (method 1). 1H NMR (500 MHz, chloroform-d) δ=5.35 (br. s., 1H), 5.19 (d, J=6.1 Hz, 1H), 4.73 (d, J=1.9 Hz, 1H), 4.60 (s, 1H), 4.15 (q, J=7.1 Hz, 2H), 2.58-2.47 (m, 2H), 2.33-2.27 (m, 2H), 2.23-1.94 (m, 6H), 1.70 (s, 3H), 1.27 (t, 3H), 1.07 (s, 3H), 1.79-0.82 (m, 34H).
