Reaction Steps
To a sealable flask containing methyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-amino-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)-2-fluorobenzoate (50 mg, 0.089 mmol) was added potassium iodide (39.9 mg, 0.240 mmol) and phosphoric acid, potassium salt (83 mg, 0.392 mmol). The mixture was diluted with acetonitrile (1 mL) and a solution of the crude mixture from the reaction above (1.718 mL, 0.445 mmol) was added. The mixture was flushed with N2 and the vial was sealed and heated to 120° C. After stirring the mixture for 66 h it was cooled to rt. The mixture was adsorbed to silica gel and was purified by flash chromatography using a 12 g Thomson silica gel column and a 0-5% MeOH in DCM gradient. The fractions containing the expected product were combined and concentrated under reduced pressure to give benzoic acid, 4-[(1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-[[3-(1,1-dioxido-4-thiomorpholinyl)propyl]amino]-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-5a,5b,8,8,11a-pentamethyl-1-(1-methylethenyl)-1H-cyclopenta[a]chrysen-9-yl]-2-fluoro-, methyl ester (43 mg, 0.058 mmol, 65.6% yield) as a yellow film. LCMS: m/e 737.5 (M+H)+, 1.88 min (method 2).
