Reaction Steps
To a solution of I2 (117 mg, 0.46 mmol) in CH2Cl2/MeOH (9:1, 130 mL) was added dropwise a solution of bis-trityl 8F (50 mg, 0.046 mmol) over 30 minutes. After a further 30 min the reaction was quenched by the addition of sodium thiosulfate (0.05M, 50 mL) followed by brine (20 mL). The organic phase was separated and the aqueous phase extracted with CH2Cl2 (3×25 mL). The combined organic phase was dried (MgSO4) before concentration in vacuo gave a white solid. Purification by column chromatography on silica gel (1-3% MeOH/CH2Cl2) gave bicyclic depsipeptide 9F (19 mg, 0.032 mmol, 69%) as a white solid: [α]25D −76.7 (c 0.60, MeOH); 1H-NMR (400 MHz, CDCl3) δ 8.15 (d, J=4.0 Hz, 1H), 7.35 (d, J=6.5 Hz, 1H), 7.23 (t, J=5.5 Hz, 1H), 7.11 (d, J=9.0 Hz, 1H), 6.05 (ddt, J=15.5, 7.0, 2.0 Hz, 1H), 5.84-5.73 (m, 2H), δ 4.97 (td, J=8.0, 4.5 Hz, 1H), 4.18-4.01 (m, 3H), 3.61 (dd, J=15.1, 8.0 Hz, 1H), 3.24 (dd, J=10.5, 6.5 Hz, 1H), 2.95-2.75 (m, 5H), 2.73-2.62 (m, 3H), 2.51 (dd, J=13.6, 2.0 Hz, 1H), 2.42 (ddd, J=18.0, 9.0, 3.5 Hz, 1H), 2.19-2.04 (m, 2H), 1.83 (s, 9H), 0.98 (d, J=6.5 Hz, 3H), 0.92 (d, J=6.5 Hz, 3H); 13C-NMR (100 MHz, CDCl3) δ 175.7 (C), 171.8 (C), 171.7 (C), 170.9 (C), 169.9 (C), 168.2 (C), 130.2 (CH), 129.6 (CH), 82.6 (C), 69.4 (CH), 65.4 (CH), 57.6 (CH), 53.8 (CH), 42.4 (CH2), 40.0 (2×CH2), 38.6 (CH2), 34.1 (CH2), 33.1 (CH2), 28.2 (CH3), 27.4 (CH), 24.9 (CH2), 20.6 (CH3), 20.2 (CH3); LRMS (ES+) m/z 623 (90%, [M+Na]+), 601 (100%, [M+H]+).
