Reaction Steps
To a solution of tert-butyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(aminomethyl)-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)benzoate (15 mg, 0.025 mmol) in DCM (4 mL) was added TFA (0.4 ml, 5.19 mmol) and the mixture was stirred at room temperature. The color of the solution turned pinkish. After 6 h, the solvent was removed in vacuo and the crude was purified by reverse phase prep. HPLC to afford the title compound as a white foam (12 mg, 80%). LCMS: m/e 544.49 (MH+), 2.60 min (method 3). 1H NMR (500 MHz, MeOD) δ ppm 7.94 (2H, d, J=8.5 Hz), 7.24 (2H, d, J=8.5 Hz), 5.32 (1H, dd, J=6.3, 1.7 Hz), 4.77 (1H, d, J=1.8 Hz), 4.66 (1H, s), 3.10-3.24 (1H, m), 2.73-2.84 (1H, m), 2.50 (1H, td, J=10.6, 5.6 Hz), 2.17 (1H, dd, J=17.1, 6.4 Hz), 1.98-2.11 (1H, m), 1.67-1.89 (8H, m), 1.54-1.66 (3H, m), 1.44-1.56 (5H, m), 1.33-1.45 (2H, m), 1.27-1.34 (3H, m), 1.23-1.28 (1H, m), 1.15-1.24 (4H, m), 1.11 (3H, s), 1.06 (3H, s), 0.92-1.02 (6H, m).
