Reaction Steps
To a solution of tert-butyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-3a-((2-(pyridin-2-yl)ethylamino)methyl)-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 (0.119 g, 0.127 mmol) in DCM (1 ml) was added TFA (0.4 ml, 5.19 mmol). The mixture was stirred at rt for 3.5 h and the mixture was concentrated under reduced pressure. The residue was purified by prep. HPLC. The fractions containing the expected product were combined and concentrated under reduced pressure to give the title compound as a light-yellow foam (61 mg, 0.094 mmol, 74.3% yield). LCMS: m/e 647.4 (M−H)−, 2.20 min (method 6). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 8.42-8.48 (m, 1H),7.95 (d, J=8.28 Hz, 2H), 7.65 (td, J=7.65, 1.76 Hz, 1H), 7.17-7.24 (m, 2H), 7.14 (d, J=8.03 Hz, 2H), 5.29 (d, J=4.52 Hz, 1H), 4.71 (br. s., 1H), 4.61 (br. s., 1H), 3.45-3.59 (m, 2H), 3.18-3.32 (m, 3H), 2.74 (d, J=12.30 Hz, 1H), 2.45 (br. s., 1H), 1.70 (s, 3H), 1.05 (s, 3H), 1.01 (s, 3H), 0.98-2.13 (m, 24H), 0.96 (s, 3H), 0.94 (br. s., 3H), 0.92 (br. s., 3H).
