To a vial containing 4-((3,3-dimethylcyclobutyl)(7-fluoroquinolin-3-ylamino)methyl)benzoic acid (11.0 mg, 0.0290 mmol) was added 3-aminopropionic acid ethyl ester hydrochloride (4.90 mg, 0.0320 mmol), 1-Hydroxy-7-azabenzotriazole (4.80 mg, 0.0350 mmol) and 1-ethyl-3-(3-dimethylamino propyl)carbodiimide hydrochloride (6.70 mg, 0.0350 mmol). Anhydrous methylene chloride (0.290 mL) was added followed by triethylamine (0.005 mL, 0.0380 mmol). After 2 h, the reaction was diluted with methylene chloride and quenched with a saturated solution of ammonium chloride. The aqueous layer was extracted three times with methylene chloride. The combined organic layers were dried with sodium sulfate, filtered, and concentrated to give 16.0 mg of crude material. Purification by silica gel flash chromatography (0-70% ethyl acetate in heptane) provided ethyl 3-(4-((3,3-dimethylcyclobutyl)(7-fluoroquinolin-3-ylamino)methyl)benzamido)propanoate (6.20 mg, 45% yield) as a yellow solid. 1H NMR (400 MHz, CDCl3, δ): 8.50 (d, J=2.3 Hz, 1H), 7.75-7.68 (m, 2H), 7.54 (dd, J=9.9, 2.5 Hz, 1H), 7.45-7.41 (m, 2H), 7.38 (dd, J=9.1, 6.0 Hz, 1H), 7.14 (td, J=8.7, 2.7 Hz, 1H), 6.80 (t, J=5.9 Hz, 1H), 6.70 (d, J=2.7 Hz, 1H), 4.40 (s, 1H), 4.23 (dd, J=9.4, 4.1 Hz, 1H), 4.20-4.08 (m, 2H), 3.70 (q, J=6.2 Hz, 2H), 2.62 (t, J=6.0 Hz, 2H), 2.52 (sxt, J=8.8 Hz, 1H), 2.09-1.97 (m, 1H), 1.71 (dd, J=19.7, 0.4 Hz, 2H), 1.63 (dd, J=8.0, 4.1 Hz, 1H), 1.31-1.21 (m, 3H), 1.13 (s, 3H), 1.09 (s, 3H). (M+1): 478.3.
