Reaction Steps
To a solution of tert-butyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(benzoyloxymethyl)-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)benzoate (7.2 g, 10.21 mmol) in 1,4-dioxane (75 ml) and water (25 ml) was added lithium hydroxide (1.285 g, 30.6 mmol) and the mixture was stirred at 75° C. Dioxane (50 ml) was added to dissolve all solids and the stirring was continued for 24 h. The solvent was removed and the residue was redissolved into CH2Cl2, the insoluble white solid was collected to afford 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(hydroxymethyl)-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)benzoic acid (2.2 g, 39.5%) LCMS: m/e 545.4 (MH+), 2.68 min (method 2).
