Reaction Steps
To a solution of methyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((2-((1S,4S)-2,5-diazabicyclo[2.2.1]heptan-2-yl)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)benzoate (75.2 mg, 0.113 mmol) and triethyl amine (0.078 mL, 0.563 mmol) in DCM (3 mL) was added methanesulfonyl chloride (10.67 μl, 0.135 mmol). The reaction mixture was stirred at rt. After 1.5 h, the reaction mixture was diluted with DCM (25 mL) and washed with H2O (2 mL). The aqueous layer was extracted with DCM (15 mL). The combined organic layer was washed with brine, dried over MgSO4, filtered and concentrated to give methyl 4-((1R,3 aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-3a-((2-((1S,4S)-5-(methylsulfonyl)-2,5-diazabicyclo[2.2.1]heptan-2-yl)ethyl)amino)-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 as a light brown solid (69.0 mg, 78% yield). LC/MS: m/e 746.8 (M+H)+, 246 min (method 3). 1H NMR (400 MHz, CHLOROFORM-d) δ 7.88 (d, J=8.1 Hz, 2H), 7.15 (d, J=8.1 Hz, 2H), 5.25 (d, J=4.6 Hz, 1H), 4.71 (s, 1H), 4.57 (s, 1H), 4.26 (s, 1H), 3.86 (s, 3H), 3.69 (br. s., 1H), 3.58 (d, J=9.5 Hz, 1H), 3.19 (dd, J=9.4, 1.8 Hz, 1H), 2.97 (dd, J=9.8, 2.0 Hz, 1H), 2.85 (s, 3H), 2.80 (dd, J=8.3, 4.2 Hz, 2H), 2.65 (d, J=9.8 Hz, 1H), 2.61-2.44 (m, 2H), 2.07 (dd, J=17.1, 6.4 Hz, 2H), 1.95-1.68 (m, 6H), 1.66 (s, 3H), 1.65-1.37 (m, 9H), 1.31-1.06 (m, 7H), 1.04 (s, 3H), 0.96 (s, 3H), 0.94 (s, 3H), 0.89 (s, 6H).
