Reaction Steps
To a stirred solution of (1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-N-((1S,3R)-2,2-dimethyl-3-(piperidine-1-carbonyl)cyclobutyl)-9-hydroxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysene-3a-carboxamide (Example 11, 0.110 g, 1.697 mmol) 2,2-Dimethylsuccinic anhydride (0.2 ml, 1.697 mmol) and DMAP (0.044 g, 0.338 mmol) in pyridine (5 ml) were added at room temperature then the reaction mixture was refluxed for about 16 hours. After completion of the reaction (monitored by TLC), the reaction mixture was diluted with EtOAc, washed with water, 1N HCl, water, brine and dried with Na2SO4, the solvent was evaporated and purified by silica gel column (100-200 mesh, elution 15% EtOAc in hexane) to afford the title compound as an off white solid. Wt: 0.080 g: Yield: 61%; 1H NMR (300 MHz, CDCl3): δ 6.01 (d, 1H, J=8.4 Hz), 4.72 (s, 1H), 4.58 (s, 1H), 4.53-4.43 (m, 1H), 4.16-4.08 (m, 1H), 3.71-3.62 (m, 2H), 3.54-3.35 (m, 3H), 3.18-3.06 (m, 1H), 2.93-2.87 (m, 1H), 2.66 (d, 1H, J=15.9 Hz), 2.56 (d, 1H, J=15.9 Hz), 2.50-2.27 (m, 2H), 1.99-1.88 (m, 2H), 1.80-1.00 (m, 46H), 0.94, 0.92, 0.83 (s, 12H); Mass: [M+1]+ 777 (100%), [M+Na]+ 799 (80%); IR (KBr, cm−1): 3411, 2944, 2867, 1733, 1730, 1625, 1467, 1445, 1368, 1253, 1220, 1192, 1022, 977, 884, 767; M.R: 139.5° C.-141.5° C.; HPLC: 96.7%.
