Trifluoroacetic acid → 4-[[(3aS,5aR,5bR,7aR,9S,11aR,11bR,13aS)-3a-[(E)-3-hydroxy-3-oxo-prop-1-enyl]-1-isopropyl-5a,5b,8,8,11a-pentamethyl-2-oxo-4,5,6,7,7a,9,10,11,11b,12,13,13a-dodecahydro-3H-cyclopenta[a]chrysen-9-yl]oxy]-2,2-dimethyl-4-oxo-butanoic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of (E)-3-((3aS,5aR,5bR,7aR,9S,11aR,11bR,13aS)-9-((4-(tert-butoxy)-3,3-dimethyl-4-oxobutanoyl)oxy)-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-3a-yl)acrylic acid (200 mg, 0.294 mmol) in dichloromethane (6 mL) stirred at room temp was added trifluoroacetic acid (TFA) (3 mL). The reaction mixture was stirred at 20° C. for 1 h. The product was extracted with DCM (15 mL*3) and the residue was purified by preparative-HPLC to give the title compound (85 mg, 39%) as a white solid. 1H NMR (400 MHz, CHLOROFORM-d) δ=7.05 (d, J=16.1 Hz, 1H), 5.75 (d, J=16.3 Hz, 1H), 4.52 (dd, J=4.8, 11.3 Hz, 1H), 3.32-3.11 (m, 1H), 2.78-2.61 (m, 3H), 2.34-2.12 (m, 3H), 2.06-0.61 (m, 44H); LC/MS: m/z calculated 624.4. Found 625.3 (M+1)+.

Provenance & Evidence