Reaction Steps
To a slurry of N-{3-[(3-{(3β)-cholest-5-en-3-yl[(2-nitrophenyl)sulfonyl]amino}propyl)amino]-3-oxopropyl}-6-(7-nitrobenzofurazan-4-ylamino)hexanamide (23, 58 mg, 0.059 mmol) and K2CO3 (139 mg, 1.008 mmol) in N,N-dimethylformamide (8 mL) and tetrahydrofuran (2 mL), was added thiophenol (61 μL, 0.590 mmol). After 18 h at 23° C., the suspension was filtered and solvent removed in vacuo. The crude product was purified by preparative reverse-phase HPLC (gradient: 59.9% MeCN, 40% H2O, and 0.1% TFA to 99.9% MeCN, 0% H2O, and 0.1% TFA over 10 min; retention time=7.6 min) to afford 7 (15 mg, 32%) mp 101-104° C.; 1H NMR (500.13 MHz, CDCl3) δ 9.54 (br s, 1H), 8.50 (d, J=8.9 Hz, 1H), 8.42 (br s, 1H), 8.01 (t, J=5.7, 1H), 7.82 (t, J=5.7 Hz, 1H), 6.39 (d, J=6.4 Hz, 1H), 5.36 (d, J=4.7 Hz, 1H), 3.43 (m, 1H), 3.22 (m, 1H), 3.11 (m, 2H), 2.93-2.84 (m, 3H), 2.39-2.28 (m, 2H), 2.22 (t, J=7.0 Hz, 2H), 2.04 (t, J=7.4 Hz, 2H), 1.97-0.94 (m, 36H), 0.92 (s, 3H), 0.86 (d, J=6.5 Hz, 3H), 0.84 (d, J=2.4 Hz, 3H), 0.82 (d, J=2.4 Hz, 3H), 0.61 (s, 3H); 13C NMR (125 MHz, DMSO d6) δ 171.9, 170.9, 145.1, 144.4, 144.1, 138.5, 137.9 122.4, 120.5, 99.0, 56.6, 56.0, 55.5, 49.3, 43.3, 41.8 (×2), 41.6, 40.5, 36.4, 36.1 (×2), 35.6, 35.5 (×2), 35.3, 35.2, 35.1, 34.3, 31.2, 27.7, 27.4, 27.3, 26.3, 26.0, 24.9, 24.4, 23.8, 23.2, 22.6, 22.4, 20.4, 18.7, 18.5, 11.6; IR (film) νmax 3257, 3093, 2940, 2858, 1636, 1548, 1377 cm−1; CI m/z 790.5605 (MH+, C45H72N7O5 requires 790.5595).
