To a solution of Example 218B (150.0 mg, 0.51 mmol) in tetrahydrofuran (10 mL) was added N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (97.0 mg, 0.51 mmol), 1-hydroxybenzotriazole (69.0 mg, 0.51 mmol), triethylamine (178.0 μL, 1.28 mmol), and 5-chloro-2-methoxybenzoic acid (Aldrich) (95.0 mg, 0.51 mmol). The mixture was stirred overnight at 80° C., and then diluted with ethyl acetate, washed with 1 M aqueous NaHCO3, dried (Na2SO4), filtered and concentrated. Purification by preparative HPLC on a Waters Symmetry C8 column (40 mm×100 mm, 7 μm particle size) using a gradient of 10% to 100% acetonitrile: ammonium acetate (10 mM) over 15 minutes at a flow rate of 70 mL/minutes afforded the title compound. 1H NMR (300 MHz, dimethylsulfoxide-d6) δ 2.75 (t, J=5.4 Hz, 2H), 3.25 (s, 3H), 3.69 (t, J=5.3 Hz, 2H), 3.80 (s, 3H), 3.95 (t, J=5.4 Hz, 1H), 4.27 (t, J=5.3 Hz, 2H), 4.58 (s, 2H), 7.12 (d, J=8.8 Hz, 1H), 7.46 (dd, J=9.0, 2.9 Hz, 1H), 7.69 (d, J=2.7 Hz, 1H); MS (ESI+) m/z 383 (M+H)+. Anal. Calculated for C17H19ClN2O4S: C, 53.33; H, 5.00; N, 7.32. Found: C, 53.21; H, 4.80; N, 7.27.
