Reaction Steps
To a stirred solution of (1R,3aS,5aR,5bR,7aR,9S,11aR,11bR,13aR,13bR)-9-acetoxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysene-3a-carboxylic acid (0.4 g, 0.803 mmol) in DCM (1 ml) (COCl)2 (0.69 ml, 8.03 mmol) in DCM (4 ml) was added at about 0° C. and the reaction mixture was stirred at room temperature for about 3 hours. After completion of the reaction (monitored by TLC) the solvent was evaporated under nitrogen atmosphere and dissolved in DCM (4 ml), which was added to a stirred solution of ((1R,3S)-3-amino-2,2-dimethylcyclobutyl)(piperidin-1-yl)methanone (Intermediate 12, 0.306 g, 1.45 mmol) in DCM (5 ml) and Et3N (0.22 ml, 1.61 mmol) at about 0° C. and allowed to stir at room temperature for about 16 hours. After completion of the reaction (monitored by TLC) the reaction mixture was diluted with DCM and washed with water, 1N HCl, water, brine and dried over Na2SO4, the solvent was evaporated and purified by silica gel column (100-200 mesh, elution 10% EtOAc in hexane) to afford the title compound as an off white solid. Wt: 0.380 g: Yield: 68.4%; δ 5.94 (d, 1H, J=7.8 Hz), 4.74 (s, 1H), 4.59 (s, 1H), 4.54-4.41 (m, 1H), 4.17-4.05 (m, 1H), 3.74-3.62 (m, 1H), 3.37 (brs, 2H), 3.18-3.07 (m, 1H), 2.89 (t, 1H, 7.8 Hz), 2.51-2.40 (m, 1H), 2.39-2.28 (m, 2H), 2.04 (s, 3H), 2.01-1.84 (m, 2H), 1.81-1.75 (m, 1H), 1.74-1.45 (m, 7H), 1.44-1.21 (m, 15H), 1.21-1.09 (m, 2H), 0.95, 0.93 (s, 9H), 0.83-0.82 (m, 12H); Mass: [M+Na]+ 714 (100%); IR (KBr, cm−1): 3372, 2943, 2864, 1736, 1730, 1652, 1636, 1623, 1501, 1459, 1444, 1369, 1248, 1192, 1024, 979, 881, 853.
