Reaction Steps
To a solution of 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-5a,5b,8,8,11a-pentamethyl-3a-((2-(methylamino)acetamido)methyl)-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, example 139, (10 mg, 0.016 mmol) and formaldehyde (0.488 mg, 0.016 mmol) in MeOH (1 ml) was added acetic acid (1.860 mL, 0.033 mmol) and sodium cyanoborohydride (1.022 mg, 0.016 mmol). A clear solution was formed soon after mixing. The mixture was stirred at rt for 2 h, LC/MS showed the mass of the expected product. The mixture was diluted with 7 ml of sat. NaHCO3 and was extracted with dichloromethane (3×7 ml). The combined organic layers were dried with Na2SO4. The drying agent was removed by filtration and the filtrate was concentrated under reduced pressure to afford the title compound as a white solid (2 mg, 18.6%). LCMS: m/e 629.4 (MH+), 2.72 min (method 3). 1H NMR (400 MHz, MeOD) δ ppm 7.90 (d, J=8.6 Hz, 2H), 7.20 (d, J=8.3 Hz, 2H), 5.19-5.42 (m, 1H), 4.72 (d, J=1.8 Hz, 1H), 4.59 (s, 1H), 3.93 (s, 2H), 3.58 (br. s., 1H), 3.04-3.17 (m, 1H), 2.89 (s, 6H), 2.46-2.60 (m, 1H), 2.10-2.18 (m, 2H), 1.80 (br. s., 2H), 1.65-1.77 (m, 7H), 1.63 (s, 1H), 1.58 (br. s., 2H), 1.38-1.55 (m, 4H), 1.19-1.34 (m, 4H), 1.13-1.19 (m, 4H), 1.06-1.13 (m, 2H), 1.04 (s, 3H), 1.02 (s, 3H), 0.95 (s, 3H), 0.93 (s, 3H).
