Reaction Steps
To a solution of 1-tert-butyl 4-((3aS,5aR,5bR,7aR,9S,11aR,11bR,13aS)-1-isopropyl-5a,5b,8,8,11a-pentamethyl-2-oxo-3a-((E)-3-oxo-3-(((S)-1-(pyridin-2-yl)ethyl)amino)prop-1-en-1-yl)-3,3a,4,5,5a,5b,6,7,7a,8,9,10,11,11a,11b,12,13,13a-octadecahydro-2H-cyclopenta[a]chrysen-9-yl) 2,2-dimethylsuccinate (480 mg, 0.611 mmol) in dichloromethane (10 mL) stirred at rt was added TFA (5 mLl). The reaction mixture was stirred at rt for 2 h. Then, it was evaporated in vacuo to get crude product. This material was purified by preparative-HPLC to provide the title compound as a trifluoroacetic acid salt (220 mg, 0.261 mmol, 42.7%) as a light yellow solid. 1H NMR (400 MHz, CHLOROFORM-d) δ=9.43 (d, J=7.0 Hz, 1H), 8.75 (d, J=4.5 Hz, 1H), 8.33 (t, J=7.7 Hz, 1H), 7.94 (d, J=7.8 Hz, 1H), 7.77 (t, J=6.4 Hz, 1H), 6.77 (d, J=15.8 Hz, 1H), 5.89 (d, J=15.8 Hz, 1H), 5.50-5.27 (m, 1H), 4.50 (dd, J=5.3, 10.8 Hz, 1H), 3.29-3.05 (m, 1H), 2.76-2.44 (m, 3H), 2.31-2.00 (m, 3H), 2.03-0.51 (m, 47H); LC/MS: m/z calculated 728.5. Found 729.3 (M+1)+.
