Reaction Steps
(3S,7S,8S,9S)-3-amino-7,8-bis(isopentyloxy)-9-methyl-1,5-dioxonan-2-one (130 mg, 0.376 mmol) and 3-hydroxy-4-methoxypicolinic acid (70.0 mg, 0.414 mmol) were diluted with DCM (3763 μl). PyBOP (215 mg, 0.414 mmol) was added, followed by N-ethyl-N-isopropylpropan-2-amine (216 μl, 1.242 mmol), and the mixture was stirred at room temperature until thin layer chromatography (TLC) indicated complete consumption of starting material. The reaction mixture was purified by column chromatography (SiO2; hexanes/EtOAc) to furnish the title compound (79.1 mg, 0.159 mmol, 42.3% yield) as a white solid: mp 61-70° C.; IR (thin film) 3530, 3371, 2955, 2873, 1750, 1649, 1529, 1262 cm−1; 1H NMR (400 MHz, CDCl3) δ 11.94 (s, 1H), 8.67 (d, J=8.1 Hz, 1H), 8.01-7.98 (m, 1H), 6.87 (d, J=5.2 Hz, 1H), 5.04 (ddd, J=8.2, 6.8, 5.0 Hz, 1H), 5.01-4.89 (m, 1H), 4.05 (dd, J=11.9, 6.8 Hz, 1H), 3.94 (s, 3H), 3.92-3.85 (m, 1H), 3.85-3.78 (m, 2H), 3.66-3.58 (m, 2H), 3.57-3.48 (m, 2H), 3.26-3.14 (m, 2H), 1.69 (dp, J=13.4, 6.7 Hz, 2H), 1.51-1.38 (m, 7H), 0.90 (dt, J=6.2, 2.7 Hz, 12H); 13C NMR (101 MHz, CDCl3) δ 170.30, 168.94, 155.32, 148.72, 140.66, 130.22, 109.56, 85.02, 83.63, 75.28, 73.94, 73.17, 72.48, 69.35, 56.09, 52.12, 39.23, 38.95, 24.96, 22.91, 22.67, 22.62, 22.50, 18.59; HRMS-ESI (m/z) [M+Na]+ calcd for C25H40N2NaO8, 519.2677, found 519.2687.
