Following general procedure A, reaction of hyodeoxycholic acid (0.050 g, 0.127 mmol) with di-tert-butyl butane-1,4-diylbis((3-aminopropyl)carbamate) (6a) (0.026 g, 0.0637 mmol), PyBop (0.073 g, 0.140 mmol) and DIPEA (0.067 mL, 0.382 mmol) in DMF (2 mL) afforded di-tert-butyl butane-1,4-diylbis((3-((R)-4-((3R,5R,6S,8S,9S,10R,13R,14S,17R)-3,6-dihydroxy-10,13-dimethylhexadecahydro-1H-cyclopenta[a]phenanthren-17-yl)pentanamido)propyl)carbamate) (0.056 g, 76%) as a clear colorless oil. Following general procedure C, a sub-sample of the product (0.047 g, 0.0408 mmol) was reacted with TFA in CH2Cl2 to afford, after chromatography, the di-TFA salt 7a (0.034 g, 71%) as a pale-yellow oil. [α ]D20.3 = +3 (c = 0.1, MeOH); Rf (RP-18, 10% aq. HCl:MeOH 1:3) 0.17; IR (ATR) νmax 3339, 2941, 1635, 1455, 1202, 1139, 1027 cm−1; 1H NMR (DMSO-d6, 400 MHz) δ 8.63 (4H, br s, NH2-29), 8.01 (2H, t, J = 5.7 Hz, NH-25), 3.84–3.79 (2H, m, H-6), 3.35–3.27 (2H, m, H-3), 3.09 (4H, q, J = 6.3 Hz, H2-26), 2.90–2.87 (8H, m, H2-28, H2-30), 2.11–2.08 (2H, m, H2-23b), 1.99–-1.95 (2H, m, H2-23a), 1.92–0.93 (56H, m, H2-1, H2-2, H2-4, H-5, H2-7, H-8, H-9, H2-11, H2-12, H-14, H2-15, H2-16, H-17, H-20, H2-22, H2-27, H2-31), 0.87 (6H, d, J = 6.4 Hz, H3-21), 0.83 (6H, s, H3-19), 0.59 (6H, s, H3-18); 13C NMR (DMSO-d6, 100 MHz) δ 173.2 (C-24), 70.0 (C-3), 65.9 (C-6), 55.9 (C-14), 55.5 (C-17), 48.3 (C-5), 46.1 (C-30), 44.6 (C-28), 42.4 (C-13), 39.5 (C-9, obscured by solvent), 39.4 (C-12, obscured by solvent), 35.5, 35.4 (C-1, C-26), 35.0, 34.9 (C-7, C-8, C-10), 34.4 (C-20), 32.3 (C-23), 31.5 (C-22), 30.3 (C-4), 29.3 (C-2), 27.7 (C-16), 26.1 (C-27), 23.9 (C-15), 23.6 (C-19), 22.7 (C-31), 20.4 (C-11), 18.3 (C-21), 11.9 (C-18); (+)-HRESIMS [M + H]+ m/z 951.7873 (calcd for C58H103N4O6, 951.7872).
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