Reaction Steps
To a solution of methyl 1-(2-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-9-(4-(methoxycarbonyl)phenyl)-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-3a-ylamino)ethyl)piperidine-4-carboxylate (40 mg) in dioxane (1 mL) was added lithium hydroxide (2.7 mg, 0.112 mmol) in water (1 mL). A white precipitate was observed. The mixture was stirred at 25° C. for 3 hours. The desired product was observed at m/e 699.7 (M+H)+, 2.703 min, method 10. The reaction mixture was neutralized with 1 N HCl to pH-4 and diluted with methlylene chloride (10 mL). The organic layer was then collected, dried over sodium sulfate and filtered. After removal of solvent, the crude product was obtained as an oil (40 mg, ˜100%) which was used without further purification. Step 2. To a solution of 1-(2-(((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-9-(4-(methoxycarbonyl)phenyl)-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-3a-yl)amino)ethyl)piperidine-4-carboxylic acid (40 mg, 0.057 mmol) in CH2Cl2 (5 ml) at rt was added dimethylamine (7.6 mg, 0.17 mmol) and HATU (65 mg, 0.18 mmol) followed by DIEA (29 mg, 0.23 mmol). The mixture was stirred for 3 hour at rt. The resulted mixture was diluted with ethyl acetate and washed with water. The organic layer was dried over sodium sulfate. The crude product was obtained after removal of solvent as a white solid (40 mg, ˜100%) which was used without further purification Step 3. 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(2-(4-(dimethylcarbamoyl)piperidin-1-yl)ethylamino)-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)benzoic acid was prepared following step 2 of the method described above for the synthesis of 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(2-(dimethylamino)-2-oxoethylamino)-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)benzoic acid. The product was isolated as a white solid (9 mg, 23.0%). LCMS: m/e 712.64 (M+H)+, 2.265 min (method 11). 1H NMR (400 MHz, METHANOL-d4) δ 7.95 (d, J=8.3 Hz, 2H), 7.25 (d, J=8.3 Hz, 2H), 5.33 (d, J=4.5 Hz, 1H), 4.87 (s, 1H), 4.74 (s, 1H), 3.65-3.38 (m, 6H), 3.16 (s, 3H), 3.05 (m, 2H), 2.96 (s, 3H), 2.75 (m, 1H), 2.23-1.85 (m, 11H), 1.82-1.74 (m, 6H), 1.70-1.48 (m, 9H), 1.44-1.28 (m, 3H), 1.22 (m, 4H), 1.13 (s, 3H), 1.08 (s, 3H), 1.00 (s, 3H), 0.98 (s, 3H),
