Reaction Steps
A reaction flask was charged with N-((3S,7S,8S,9S)-7,8-diisobutoxy-9-methyl-2-oxo-1,5-dioxonan-3-yl)-3-hydroxy-4-methoxypicolinamide (97 mg, 0.207 mmol), DMAP (40.1 mg, 0.328 mmol), and DCM. 3-Methoxypropanoyl chloride (22.5 μl, 0.207 mmol) was added and the colorless solution was stirred at room temperature under N2 overnight. The reaction mixture was concentrated and purified by column chromatography (SiO2, hexanes/EtOAc gradient) to afford the title compound (108.5 mg, 94% yield) as a sticky orange oil: IR (thin film) 3375, 2955, 2873, 1753, 1677, 1507, 1088 cm−1; 1H NMR (400 MHz, CDCl3) δ 8.67 (d, J=8.2 Hz, 1H), 8.38-8.30 (m, 1H), 7.00 (dd, J=5.7, 1.8 Hz, 1H), 5.08-4.98 (m, 1H), 4.93 (ddt, J=12.2, 8.4, 4.1 Hz, 1H), 4.00 (tt, J=7.2, 3.4 Hz, 1H), 3.93-3.84 (m, 3H), 3.85-3.64 (m, 5H), 3.64-3.55 (m, 1H), 3.41 (d, J=1.5 Hz, 3H), 3.33-3.12 (m, 5H), 2.97 (t, J=6.6 Hz, 2H), 1.82 (tt, J=12.9, 6.0 Hz, 2H), 1.43 (dd, J=6.3, 1.7 Hz, 3H), 0.97-0.85 (m, 12H); 13C NMR (101 MHz, CDCl3) δ 170.85, 169.37, 162.67, 159.42, 146.81, 141.19, 137.38, 109.88, 84.82, 83.75, 80.56, 77.70, 74.88, 74.07, 72.99, 67.58, 58.80, 56.32, 52.13, 34.61, 29.11, 28.87, 19.58, 19.46, 19.37, 18.63; ESIMS m/z 555 ([M+H]+).
