Reaction Steps
To a sealable vial was added ethyl 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)cyclohex-3-enecarboxylate (0.156 g, 0.278 mmol), ethylene bromohydrin (0.059 mL, 0.833 mmol), potassium iodide (0.138 g, 0.833 mmol), and phosphoric acid, potassium salt (0.295 g, 1.388 mmol). The mixture was diluted with acetonitrile (2 mL), was flushed with nitrogen, then was sealed and heated to 100° C. After 15 h of heating, the mixture was cooled to rt. LC/MS still showed starting material present, so an additional 0.059 mL of ethylene bromohydrin was added, the mixture was diluted with 1 mL of acetonitrile, and it was sealed and heated to 120° C. After heating the mixture for an additional 20 h, it was cooled to rt, and diluted with 10 mL of water. The solids that formed were collected by filtration and were washed with water to give ethyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((2-hydroxyethyl)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)cyclohex-3-enecarboxylate (0.145 g, 0.239 mmol, 86% yield) as an off-white solid. LCMS: m/e 606.7 (M+H)+, 2.18 min (method 1).
