Reaction Steps
The title compound was prepared in 30% 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-oxo-4-phenyl-3-oxazolidineacetic acid was used instead of 3-(dimethylamino)propionic acid hydrochloride in Step 1. LCMS: m/e 733.5 (M+H)+, 2.25 min (method 6). 1H NMR (400 MHz, 1:1 CDCl3:MeOD) δ=7.92 (d, J=8.3 Hz, 2H), 7.47-7.39 (m, 3H), 7.37-7.32 (m, 2H), 7.20 (d, J=8.3 Hz, 2H), 6.60 (s, 1H), 5.28 (d, J=4.5 Hz, 1H), 5.04 (t, J=8.3 Hz, 1H), 4.75 (t, J=8.9 Hz, 1H), 4.71 (s, 1H), 4.61 (br. s., 1H), 4.25-4.19 (m, 1H), 4.04 (d, J=16.3 Hz, 1H), 3.40 (d, J=16.3 Hz, 1H), 2.65-2.59 (m, 1H), 2.47 (dt, J=4.8, 11.0 Hz, 1H), 2.37 (dd, J=8.2, 11.7 Hz, 1H), 2.11 (dd, J=6.3, 17.1 Hz, 1H), 1.84-1.70 (m, 4H), 1.69 (s, 3H), 1.66-1.59 (m, 1H), 1.58-1.40 (m, 7H), 1.39-1.22 (m, 6H), 1.09 (br. s., 1H), 1.07 (s, 3H), 1.00 (s, 6H), 0.95 (s, 3H), 0.94 (br. s., 3H).
