Reaction Steps
The title compound was prepared in 34% yield from methyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-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 following the same procedure as described for the preparation of 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(3-(dimethylamino)propanamido)-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)benzoic acid, except (S)-2-(3-(tert-butoxycarbonylamino)-2-oxopyrrolidin-1-yl)acetic acid was used instead of 3-(dimethylamino)propionic acid hydrochloride in Step 1. LCMS: m/e 770.6 (M+H)+, 2.07 min (method 6). 1H NMR (400 MHz, 1:1 CDCl3:MeOD) δ=7.92 (d, J=8.0 Hz, 2H), 7.20 (d, J=8.0 Hz, 2H), 6.83-6.60 (m, 1H), 5.29 (d, J=4.8 Hz, 1H), 4.76 (s, 1H), 4.63 (br. s., 1H), 4.32-4.16 (m, 1H), 4.07-3.84 (m, 2H), 3.44 (d, J=7.0 Hz, 2H), 2.70-2.56 (m, 2H), 2.55-2.44 (m, 1H), 2.43-2.31 (m, 1H), 2.13 (dd, J=6.3, 17.1 Hz, 1H), 2.08-1.95 (m, 1H), 1.94-1.82 (m, 2H), 1.81-1.73 (m, 2H), 1.71 (s, 3H), 1.68-1.62 (m, 1H), 1.61-1.48 (m, 6H), 1.46 (s, 9H), 1.43-1.22 (m, 6H), 1.13 (br. s., 1H), 1.10 (d, J=3.8 Hz, 3H), 1.02 (s, 6H), 0.95 (br. s., 3H), 0.94 (br. s., 3H).
