Reaction Steps
To a slurry of N-(3-{(3β)-cholest-5-en-3-yl[(2-nitrophenyl)sulfonyl]amino}propyl)-6-(7-nitrobenzofurazan-4-ylamino)hexanamide (22, 88 mg, 0.097 mmol) and K2CO3 (134 mg, 0.970 mmol) in N,N-dimethylformamide (8 mL) and tetrahydrofuran (2 mL), was added thiophenol (79 μL, 0.767 mmol). After 18 h at 23° C., the suspension was filtered and solvent removed in vacuo. Purification by preparative reverse-phase HPLC (gradient: 69.9% MeCN, 30% H2O, and 0.1% TFA to 99.9% MeCN, 0% H2O, and 0.1% TFA over 10 min; retention time=7.7 min) afforded 8 (20 mg, 29%) mp 78-80° C.; 1H NMR (500 MHz, DMSO d6) δ 9.54 (br s, 1H), 8.50 (d, J=8.8 Hz, 1H), 8.43 (br s, 1H), 7.99 (t, J=5.8, 1H), 6.38 (d, J=9.0 Hz, 1H), 5.34 (br s, 1H), 3.43 (m, 1H), 3.11 (m, 2H), 2.94-2.81 (m, 3H), 2.30 (m, 2H), 2.09 (t, J=7.3 Hz, 2H), 1.92-0.94 (m, 35H), 0.90 (s, 3H), 0.87 (d, J=6.4 Hz, 3H), 0.84 (d, J=2.4 Hz, 3H), 0.83 (d, J=2.4 Hz, 3H), 0.60 (s, 3H); 13C NMR (125.8 MHz, DMSO d6) δ 172.7, 145.1, 144.4, 144.1, 138.5, 137.9 122.4 (×2), 99.0, 56.6, 56.0, 55.5, 49.3, 43.3, 41.8, 41.7, 41.6, 36.4, 36.1, 35.6, 35.4, 35.1 (×2), 34.3, 31.2 (×2), 27.7, 27.4, 26.3, 26.1, 24.9, 24.4, 23.8, 23.7, 23.1, 22.6, 22.4, 20.4, 18.7, 18.5 (×2), 11.6; IR (film) νmax 3269, 2949, 2868, 1649, 1585, 1530, 1300 cm−1; CI m/z 719.5224 (MH+, C42H67N6O4 requires 719.5224).
