Reaction Steps
To a solution of 9F (12 mg, 0.02 mmol) and Et3SiH (10 μL, 0.06 mmol) in CH2Cl2 (1.5 mL) was added TFA (150 μL, 2.0 mmol). After 6 h the solvent was removed and the residue purified by column chromatography on silica gel (10% methanol/CH2Cl2 then +1% AcOH) to give 1° F. (5.6 mg, 0.01 mmol, 55%) as a white solid: [α]25D −63.4 (c 0.25, MeOH); 1H-NMR (400 MHz, CD3OD) δ 7.5 (1×NH observed, d, J=7.5 Hz, 1H), 5.81 (dddd, J=16.8, 6.8, 4.8, 2.5 Hz, 1H), 5.75-5.67 (m, 2H), 4.62 (ddd, J=11.0, 8.0, 5.5 Hz 1H), 4.28 (d, J=17.5 Hz, 1H), 4.15 (dd, J=9.0, 6.0 Hz, 1H), 3.78 (d, J=17.5 Hz, 1H), 3.43 (d, J=10.5 Hz, 1H), 3.20-3.10 (m, 2H), 3.07-3.00 (m, 2H), 2.94-2.81 (m, 1H), 2.82 (dd, J=13.2, 2.2 Hz, 1H), 2.73-2.50 (m, 4H), 2.38 (q, J=7.0 Hz, 1H), 2.23-1.99 (m, 2H), 0.98 (d, J=6.5 Hz, 3H), 0.92 (d, J=6.5 Hz, 3H); 13C-NMR (100 MHz, CD3OD) δ 176.5 (C), 174.0 (C), 173.5 (C), 173.0 (C), 171.6 (C), 169.5 (C), 131.4 (CH), 131.3 (CH), 72.1 (CH), 66.0 (CH), 58.5 (CH), 57.0 (CH), 42.7 (CH2), 39.7 (CH2), 39.4 (CH2), 36.8 (CH2), 31.8 (CH2), 31.6 (CH2), 28.2 (CH3), 26.6 (CH2), 20.6 (CH3), 20.5 (CH3); LRMS (ES−) m/z 543 (100%, [M−H]−).
