Reaction Steps
Pd/C (10 wt %, 8.7 μg) and azide 8 (18.0 mg, 0.0247 mmol) were added to a 0.20 M solution of 18 (0.0988 mmol) in 0.40 mL of EtOAc (filtered through activated alumina). The reaction mixture was stirred under a hydrogen atmosphere for 26 h and then filtered through a plug of Celite with washing of the filter pad with EtOAc. The filtrate was concentrated, and a 1:1 mixture of deoxygenated H2O/dioxane (4.0 mL) was added. The mixture was stirred for 20 h at rt and concentrated. Reverse-phase HPFC (20:80 to 100:0 MeCN:H2O) followed by lyophilization afforded 9.3 mg (48%) of 6 as an amorphous solid. [α]D23=−2.0 (c=0.6, MeOH). IR: 1226, 1496, 1542, 1741, 2964 cm−1. 1H NMR (500 MHz, MeOD): δ 0.81 (d, 3H, J=6.5 Hz), 0.87 (d, 3H, J=6.5 Hz), 0.89 (d, 3H, J=7.0 Hz), 0.92 (t, 3H, J=7.5 Hz), 0.98 (d, 3H, J=6.5 Hz), 1.06 (d, 3H, J=6.5 Hz), 1.12-1.21 (m, 1H), 1.17 (d, 3H, J=7.0 Hz), 1.58-1.70 (m, 2H), 1.77-1.91 (m, 2H), 1.92-2.05 (m, 3H), 2.06-2.17 (m, 2H), 2.16 (s, 3H), 2.35 (s, 6H), 2.46-2.57 (m, 2H), 2.92 (d, 2H, J=5.5 Hz), 3.11 (q, 2H, J=16.2 Hz), 4.28-4.50 (br s, 1H), 4.32-4.38 (m, 1H), 4.70 (d, 1H, J=8.5 Hz), 5.46 (d, 1H, J=12.0 Hz), 5.87 (d, 1H, J=11.0 Hz), 6.05 (d, 1H, J=12.0 Hz), 7.12-7.18 (m, 1H), 7.19-7.26 (m, 4H), 8.09 (s, 1H). 13C NMR (125 MHz, MeOD) δ 11.1, 16.6, 19.0, 20.3, 20.8, 20.9, 22.9, 25.5, 26.2, 26.9, 32.4, 35.9, 37.6, 39.1, 39.7, 42.1, 44.5, 45.8, 51.2, 55.2, 62.7, 70.8, 125.6, 127.5, 129.4, 130.6, 139.7, 150.9, 162.7, 170.8, 171.7, 172.0, 173.3, 176.5, 181.8. HRMS (FAB) calcd for C40H62N5O9S (M+H): 788.4268. Found: 788.4256.
