Reaction Steps
To a solution of 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((3-carboxypropanamido)methyl)-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 (20 mg, 0.037 mmol) in methanol (2 ml) was added TFA to form a 0.1% v/v TFA-methanol solution. The mixture was stirred at rt for 28 h. The solvent was removed in vacuo and the resulting residue was purified by prep. HPLC. The product was isolated as a white solid (1.1 mg, 4.55%). LCMS: m/e 658.5 (MH+), 2.90 min (method 3). 1H NMR (400 MHz, MeOD) δ ppm 7.94 (d, J=8.5 Hz, 2H), 7.16-7.34 (m, 2H), 5.32 (dd, J=6.4, 1.6 Hz, 1H), 4.74 (d, J=2.0 Hz, 1H), 4.62 (s, 1H), 3.68 (s, 3H), 3.54 (d, J=13.6 Hz, 1H), 3.04 (d, J=13.8 Hz, 1H), 2.57-2.71 (m, 2H), 2.44-2.57 (m, 2H), 2.17 (dd, J=17.2, 6.4 Hz, 1H), 2.09 (dd, J=13.1, 1.8 Hz, 1H), 1.85 (dd, J=12.2, 3.4 Hz, 2H), 1.65-1.82 (m, 8H), 1.61 (br. s., 2H), 1.53 (d, J=10.5 Hz, 3H), 1.48 (d, J=2.0 Hz, 1H), 1.35-1.45 (m, 3H), 1.24-1.35 (m, 3H), 1.16-1.24 (m, 4H), 1.02-1.16 (m, 8H), 0.99 (s, 3H), 0.95 (s, 3H).
