Reaction Steps
To a solution of (S)-benzyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((2-((1S,4S)-2-oxa-5-azabicyclo[2.2.1]heptan-5-yl)ethyl)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 in THF (1.5 mL) and MeOH (0.5 mL) was added 1N lithium hydroxide (0.115 mL, 0.115 mmol). The reaction was stirred at 75° C. After 3 h the reaction mixture was concentrated and the crude material was dissolved in THF (2 mL)/H2O (150 μL) and purified by reverse phase prep-HPLC using prep-HPLC method 15 and dried under vacuum to give (S)-4-((1R,3 aS,5aR,5bR,7aR,11aS,11bR,13 aR,13bR)-3a-((2-((1S,4S)-2-oxa-5-azabicyclo[2.2.1]heptan-5-yl)ethyl)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-enecarboxylic acid (21 mg, 0.023 mmol, 80% yield) as a white solid. LC/MS: m/e 659.5 (M+H)+, 34.14 min (method 8). 1H NMR (400 MHz, 1:1 CDCl3:METHANOL-d4) δ 5.33 (br. s., 1H), 5.17 (d, J=4.6 Hz, 1H), 4.78 (s, 1H), 4.70 (br. s., 1H), 4.52 (s, 1H), 4.03 (d, J=8.6 Hz, 1H), 3.75 (br. s., 1H), 3.72 (d, J=8.6 Hz, 1H), 3.18-3.09 (m, 2H), 3.09-2.92 (m, 4H), 2.79-2.64 (m, 2H), 2.53-2.42 (m, 1H), 2.31-2.23 (m, 2H), 2.16 (br. s., 2H), 2.04-1.93 (m, 8H), 1.81-1.73 (m, 2H), 1.72 (s, 3H), 1.69-1.63 (m, 1H), 1.61-1.33 (m, 12H), 1.30 (dd, J=12.2, 3.4 Hz, 1H), 1.24 (br. s., 1H), 1.20-1.14 (m, 1H), 1.12-1.09 (m, 3H), 1.05 (s, 3H), 0.97 (s, 3H), 0.90 (s, 3H), 0.88 (s, 3H)
