Reaktionsschritte
A flask containing benzyl 1-hydroxy-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)cyclohex-3-enecarboxylate (0.113 g, 0.221 mmol) and (1R,3aS,5aR,5bR,7aR,11aR,11bR,13 aR,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 trifluoromethanesulfonate (0.082 g, 0.147 mmol) was diluted with 1,4-dioxane (1 mL) and water (0.25 mL). To the mixture was added sodium carbonate hydrate (0.075 g, 0.605 mmol) and the mixture was degassed with nitrogen for five minutes. To the mixture was added palladium tetrakis (5.10 mg, 4.41 mmol) then the flask was purged then refilled with nitrogen three times. The mixture was heated to 85° C. for 4 h then was cooled to rt and was purified by flash chromatography using a 20-80% ethyl acetate in hexanes gradient and a 25 g silica gel column. The fractions containing the expected product were combined and concentrated under reduced pressure to give benzyl 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)-1-hydroxycyclohex-3-enecarboxylate (0.053 g, 0.083 mmol, 56.3% yield) as an off-white foam. LCMS: m/e 640.6 (M+H)+, 1.91 min (method 1).
