Reaction Steps
A mixture of (1R,3aS,5aR,5bR,7aR,11aR,13aR,13bR)-methyl 5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-9-(trifluoromethylsulfonyloxy)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysene-3a-carboxylate (240 mg, 0.399 mmol), 3-boronobenzoic acid (133 mg, 0.799 mmol), sodium carbonate (212 mg, 1.997 mmol) and Pd(Ph3P)4 (46.2 mg, 0.040 mmol) in DME (2.000 ml) and water (2 ml) was heated to 100° C. for 3 hours. TLC and LCMS indicated starting material was consumed, and the desired product was formed. The reaction mixture was cooled to room temperature, neutralized with 1N HCl, extracted with ethyl acetate, dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by biotage using ethyl acetate/hexanes (0-100%) ethyl acetate/hexanes to give the desired product 3-((1R,3aS,5aR,5bR,7aR,11aS,13aR,13bR)-3a-(methoxycarbonyl)-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 as a white solid (120 mg, 50%). LCMS: m/e 571.47 (M−H)−, 3.91 min (method 5). 1H NMR (500 MHz, DMSO-D6) δ ppm 0.88 (d, J=5.19 Hz, 6H), 0.92 (s, 3H), 0.95 (s, 3H), 0.98 (s, 3H), 1.00-1.56 (m, 15H), 1.57-1.73 (m, 5H), 1.73-1.86 (m, 2H), 2.07 (dd, J=17.24, 6.26 Hz, 1H), 2.11-2.17 (m, 1H), 2.18-2.28 (m, 1H), 2.85-3.03 (m, 1H), 3.61 (s, 3H), 4.59 (s, 1H), 4.72 (d, J=1.83 Hz, 1H), 5.25 (d, J=4.58 Hz, 1H), 7.33 (d, J=7.32 Hz, 1H), 7.40 (t, J=7.63 Hz, 1H), 7.65 (s, 1H), 7.82 (d, J=7.93 Hz, 1H).
