Reaction Steps
To a solution of (1R,5S)-tert-butyl 3-(2-(((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-9-(4-(methoxycarbonyl)phenyl)-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-3a-yl)amino)ethyl)-3,6-diazabicyclo[3.1.1]heptane-6-carboxylate (123 mg, 0.160 mmol) in DCM (3 mL) was added TFA (0.5 mL, 6.49 mmol) and the mixture was stirred at rt for 1 h. The resulting brown reaction mixture was diluted with DCE (3 mL) and concentrated to a light brown foam. The material was dissolved in DCM (2 mL) and DCE (2 mL) and treated with 2N HCl in Et2O (0.5 mL, 1.0 mmol). The resulting slurry was concentrated and dried under vacuum to give the title compound (108.1 mg, 0.139 mmol, 87% yield) as light grey solid. LC/MS: m/e 668.5 (M+H)+, 2.28 min (method 3). 1H NMR (400 MHz, 1:1 CDCl3:METHANOL-d4) δ 7.89 (d, J=8.3 Hz, 2H), 7.18 (d, J=8.6 Hz, 2H), 5.27 (d, J=4.4 Hz, 1H), 4.85 (s, 1H), 4.71 (s, 1H), 4.39 (d, J=5.4 Hz, 2H), 3.88 (s, 3H), 3.76 (br. s., 1H), 3.59 (br. s., 1H), 3.48 (q, J=7.1 Hz, 3H), 3.40-3.33 (m, 2H), 3.07-2.91 (m, 2H), 2.37 (d, J=10.3 Hz, 1H), 2.25-1.89 (m, 7H), 1.83 (d, J=12.0 Hz, 1H), 1.77 (br. s., 1H), 1.73-1.71 (m, 3H), 1.67 (br. s., 1H), 1.65-1.58 (m, 2H), 1.57-1.38 (m, 8H), 1.37-1.29 (m, 1H), 1.27-1.22 (m, 1H), 1.13 (s, 3H), 1.08 (s, 3H), 1.00 (s, 3H), 0.92 (s, 3H), 0.91 (s, 3H).
