Reaction Steps
A solution of methyl hex-5-enoate (21.4 mg, 0.167 mmol) in THF (3 mL) under argon was cooled to 0° C. and 9-BBN (0.5 M in THF) (0.356 mL, 0.178 mmol) was added dropwise. The reaction mixture was warmed to rt and was stirred for 2 h. A solution of potassium phosphate tribasic (1M) (0.278 mL, 0.278 mmol) was added to the reaction mixture followed by a solution of (1R,3aS,5aR,5bR,7aR,11aR,11bR,13aR,13bR)-3a-((2-(1,1-dioxidothiomorpholino)ethyl)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 (80 mg, 0.111 mmol) in dioxane (3.00 mL). PdCl2(dppf).CH2Cl2 adduct (4.5 mg, 5.6 μmol) was then added and the reaction mixture was stirred for 16 h at 85° C. The reaction mixture was cooled to room temperature and was diluted with water (10 mL). The aqueous layer was extracted with ethyl acetate (3×10 mL). The combined organic layers were dried (sodium sulfate) and concentrated under vacuum. The product was purified by column chromatography on silica gel (0%>50% ethyl acetate in hexanes) to afford methyl 6-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((2-(1,1-dioxidothiomorpholino)ethyl)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)hexanoate (48.2 mg, 62% yield). LC/MS: m/e 699.5 (M+H)+, 2.45 min (method 3).
