Reaction Steps
To a solution of diisopropyl 6-((1R,3aS,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)spiro[3.3]hept-5-ene-2,2-dicarboxylate (0.057 g, 0.085 mmol) in ethanol (2 mL), 1,4-dioxane (2 mL) and acetic acid (0.02 mL, 0.349 mmol) was added palladium hydroxide (20% on carbon) (0.072 g, 0.103 mmol). The mixture as stirred under 1 atm of hydrogen overnight. After stirring the mixture for 15 h, it was filtered through a plug of celite (washed with MeOH) then the filtrate was concentrated under reduced pressure. The residue was diluted with 15 mL of sat. aq. NaHCO3 and extracted with dichloromethane (3×15 mL). The combined organic layers were dried with sodium sulfate. The drying agent was removed by filtration and the filtrate was concentrated under reduced pressure to give diisopropyl 6-((1S,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-amino-1-isopropyl-5a,5b,8,8,11a-pentamethyl-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)spiro[3.3]heptane-2,2-dicarboxylate (0.057 g, 0.085 mmol, 100% yield) as an off-white solid. 1H NMR (500 MHz, chloroform-d) δ=5.33 (d, J=5.7 Hz, 1H), 5.11-5.02 (m, 2H), 3.80-3.72 (m, 1H), 3.68-3.60 (m, 1H), 2.66 (s, 2H), 2.44 (s, 2H), 2.99-0.64 (m, 62H).
