Acetic Acid → tert-butyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-3a-((3-morpholinopropylamino)methyl)-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

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Reaction Steps

To a solution of tert-butyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-formyl-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 (0.1 g, 0.167 mmol) in DCE (2 ml) was added acetic acid (1M in DCM) (0.167 ml, 0.167 mmol) and N-(3-Aminopropyl)morpholine (0.029 ml, 0.200 mmol). The mixture was stirred for 15 minutes at rt and sodium triacetoxyborohydride (0.071 g, 0.334 mmol) was added. The mixture was stirred at rt for 1.5 h and an additional 0.1 g of sodium triacetoxyborohydride was added. The mixture was stirred overnight at rt then was quenched with 7 ml of sat. NaHCO3. The mixture was extracted with dichloromethane (3×7 ml) and the combined organic layers were dried with Na2SO4. The drying agent was removed by filtration and the filtrate was concentrated under reduced pressure. The mixture was purified by flash chromatography using a 0-10% MeOH in dichloromethane gradient. The fractions containing the expected product were combined and concentrated under reduced pressure to give the title compound as a white foam (69 mg, 0.095 mmol, 56.8% yield). LCMS: m/e 727.5 (M+H)+, 2.81 min (method 6).

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