Reaction Steps
To a solution of 1-tert-butyl 4-((3aS,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-((E)-3-(((S)-1-(4-chlorophenyl)ethyl)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 (420 mg, 0.513 mmol) in Dichloromethane (6 mL) was added TFA (3 mL, 0.513 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-(((S)-1-(4-chlorophenyl)ethyl)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 (60 mg, 0.079 mmol, 15.34%) as a white solid. 1H NMR (400 MHz, CHLOROFORM-d) δ=7.44-7.18 (m, 4H), 6.97 (d, J=15.8 Hz, 1H), 5.80-5.58 (m, 2H), 5.25-5.09 (m, 1H), 4.50 (dd, J=5.3, 10.8 Hz, 1H), 3.27-3.13 (m, 1H), 2.79-2.52 (m, 2H), 2.36-2.01 (m, 3H), 2.00-0.65 (m, 47H); LC/MS: m/z calculated 761.4. Found 762.3 (M+1)+.
