Reaction Steps
A solution of 5-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((2-(1,1-dioxidothiomorpholino)ethyl)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)-3,3-dimethylpentanoic acid (35 mg, 0.050 mmol) in DCM (2 mL) was treated with HATU (28.6 mg, 0.075 mmol), N,N-diisopropylethylamine (0.026 mL, 0.150 mmol), and hydroxylamine (1.8 mg, 0.055 mmol). The reaction mixture was stirred at rt for 16 h. The mixture was concentrated and the crude product was purified by prep HPLC (Method 10) to afford 5-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((2-(1,1-dioxidothiomorpholino)ethyl)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)-N-hydroxy-3,3-dimethylpentanamide (1.9 mg, 5% yield). LC/MS m/e 714.5 (M+H)+, 2.23 min (ionization peak, no UV) (method 3). 1H NMR (500 MHz, DMSO-d6) δ 10.29 (2, 1H), 5.20 (d, J=5.5 Hz, 1H), 4.69 (s, 1H), 4.55 (s, 1H), 3.14-3.01 (m, 4H), 2.98-2.84 (m, 4H), 2.65-2.55 (m, 3H), 2.50-2.44 (m, J=5.9 Hz, 1H), 2.40-2.31 (m, J=5.1 Hz, 1H), 1.97-0.76 (m, 28H), 1.65 (s, 3H), 1.03 (s, 3H), 0.95 (s, 3H), 0.94 (s, 9H), 0.87 (s, 3H), 0.79 (s, 3H).
