Reaction Steps
To a solution of diisopropyl 6-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-3a-((2-(1,1,1-trifluoro-N-phenylmethylsulfonamido)ethyl)amino)-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 (15 mg, 0.016 mmol) in dioxane (2 mL) and MeOH (1 mL) was added 1N NaOH (1 mL, 1 mmol). The mixture was stirred at 50° C. for 3 h. The mixture was neutralized by 1N HCl (1 mL) to pH ˜6 and solids formed were collected by filtration. The crude product was purified by preparative HPLC using method 14 to give 6-((1R,3 aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-3a-((2-(1,1,1-trifluoro-N-phenylmethylsulfonamido)ethyl)amino)-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-dicarboxylic acid in 42% yield as a solid. MS: m/e 841.5 (M+H)+, 2.52 min (method 4). 1H NMR (400 MHz, METHANOL-d4) δ 7.52-7.43 (m, 5H), 5.93 (s, 1H), 5.56-5.52 (m, 1H), 4.72 (d, J=1.8 Hz, 1H), 4.60 (s, 1H), 3.99 (s., 2H), 2.77-2.65 (m, 4H), 2.63-2.51 (m, 5H), 2.15 (dd, J=17.8, 6.5 Hz, 1H), 1.92-1.83 (m, 2H), 1.78-0.94 (m, 19H), 1.69 (s, 3H), 1.16 (s, 3H), 1.11 (s, 3H), 1.09 (s, 3H), 0.98 (s, 3H), 0.87 (s, 3H). 19F NMR (376 MHz, METHANOL-d4) δ −75.37 (s., 3F).
