Reaction Steps
To a solution of (1S,4S)-5-(2-(((1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-9-hydroxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysen-3a-yl)amino)ethyl)-2-thia-5-azabicyclo[2.2.1]heptane 2,2-dioxide (73 mg, 0.121 mmol) in DCM (2 mL) was added N,N-diisopropylethylamine (0.063 mL, 0.364 mmol), 4-(tert-butoxy)-3,3-dimethyl-4-oxobutanoic acid (49.1 mg, 0.243 mmol) (prepared as described in WO 2004014881), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (47.5 mg, 0.243 mmol) and 4-dimethylaminopyridine (29.7 mg, 0.243 mmol). The resulting solution mixture was stirred at rt. After 3.5 h, the reaction mixture was diluted with DCM (30 mL) and washed with 0.1N HCl (5 mL). The aqueous layer was extracted with DCM (25 mL). The combined organic layer was washed with 10% NaHCO3, brine, dried over MgSO4, filtered and concentrated. The crude material was purified by flash column chromatography (12 g, eluted with 97:3 DCM:MeOH) and dried under vacuum to give the title compound (83.2 mg, 87% yield) as a white solid. LC/MS: m/e 785.6 (M+H)+, 4.15 min (method 8). 1H NMR (400 MHz, CHLOROFORM-d) δ 4.71 (br. s., 1H), 4.59 (s, 1H), 4.48 (dd, J=10.6, 5.5 Hz, 1H), 3.89 (br. s., 1H), 3.51 (br. s., 1H), 3.40 (dd, J=13.0, 2.7 Hz, 1H), 3.27-3.21 (m, 1H), 3.20 (d, J=3.9 Hz, 1H), 2.90 (dd, J=13.1, 3.1 Hz, 1H), 2.86 (br. s., 1H), 2.74-2.60 (m, 1H), 2.53 (s, 3H), 2.51 (d, J=7.3 Hz, 2H), 2.41-2.32 (m, 1H), 2.02 (d, J=17.4 Hz, 1H), 1.86 (d, J=13.4 Hz, 1H), 1.82-1.73 (m, 2H), 1.68 (s, 3H), 1.66-1.50 (m, 7H), 1.43 (s, 11H), 1.42-1.30 (m, 6H), 1.26 (d, J=8.1 Hz, 2H), 1.23 (s, 3H), 1.22 (s, 3H), 1.12-1.04 (m, 2H), 1.01 (s, 3H), 0.95 (s, 3H), 0.84 (s, 6H), 0.83 (s, 3H), 0.78 (d, J=9.5 Hz, 1H).
