Reaction Steps
To a solution of 1-tert-butyl 4-((3aS,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-((E)-3-((4-chlorophenyl)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 (230 mg, 0.291 mmol) in Dichloromethane (DCM) (4 mL) was added TFA (2 mL, 0.291 mmol). The reaction mixture was stirred at r.t for 2 hs and evaporated in vacuo to afford crude product, which was purified by preparative-HPLC (Mobile Phase: A=0.05% TFA/H2O, B=MeCN) to give the product 4-(((3aS,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-((E)-3-((4-chlorophenyl)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)oxy)-2,2-dimethyl-4-oxobutanoic acid (100 mg, 0.136 mmol, 46.8%) as a white solid. 1H NMR (400 MHz, CDCl3) δ ppm 7.60-7.53 (m, 3H), 7.28 (d, J=8.4 Hz, 2H), 7.12 (d, J=15.6 Hz, 1H), 5.84 (d, J=15.6 Hz, 1H), 4.50 (dd, J=11.2, 5.2 Hz, 1H), 3.22 (m, 1H), 2.77 (d, J=11.6 Hz, 1H), 2.68 (d, J=16.0 Hz, 1H), 2.57 (d, J=15.6 Hz, 1H), 2.32 (d, J=18.8 Hz, 1H), 2.20 (d, J=19.2 Hz, 1H), 2.11 (d, J=12.0 Hz, 1H), 1.93-0.77 (m, 44H); LC/MS: m/z calculated 733.4. Found 734.3 (M+1)+.
