Reaction Steps
To a solution of 1-tert-butyl 4-((3aS,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-((E)-3-((5-chloropyridin-2-yl)amino)-3-oxoprop-1-en-1-yl)-1-isopropyl-5a,5b,8,8,11a-pentamethyl-2-oxo-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 (100 mg, 0.126 mmol) in dichloromethane (4 mL) stirred at rt was added TFA (2 mL, 26.0 mmol). The reaction mixture was stirred at rt for 1 h. The mixture was evaporated to get the crude product which was purified by preparative-HPLC to give the title compound as a TFA salt (60 mg, 55.9%). 1H NMR (400 MHz, CHLOROFORM-d) δ=11.06 (br. s., 1H), 8.54 (d, J=9.0 Hz, 1H), 8.13 (d, J=2.3 Hz, 1H), 7.83 (dd, J=2.3, 9.0 Hz, 1H), 7.10 (d, J=15.8 Hz, 1H), 6.09 (d, J=15.8 Hz, 1H), 4.52 (dd, J=4.3, 11.5 Hz, 1H), 3.30-3.12 (m, 1H), 2.82-2.52 (m, 3H), 2.38-2.08 (m, 3H), 2.04-1.75 (m, 3H), 1.75-0.60 (m, 41H); LC/MS: m/z calculated 734.4. Found 735.3 (M+1)+.
