A mixture of 2-(4-methylthiazol-5-yl)benzoxazole-4-carboxylic acid (80 mg, 0.31 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (118 mg, 0.62 mmol), 1-hydroxybenzotriazole (84 mg, 0.62 mmol) and (S)-(−)-3-aminoquinuclidine dihydrochloride (73 mg, 0.39 mmol) in DMF (5 mL) was stirred at room temperature for 10 min, then triethylamine (0.18 mL, 4.0 mmol) was added. The resulting reaction mixture was stirred at room temperature overnight. The mixture was diluted with ethyl acetate (50 mL), and then washed with a saturated solution of sodium bicarbonate. The aqueous layer was further extracted with ethyl acetate (2×100 mL). The combined organics were washed with water (2×50 mL) and brine (2×50 mL), dried (Na2SO4), filtered and concentrated. The crude material was purified by column chromatography (silica gel, 90:9:1 dichloromethane/methanol/concentrated ammonium hydroxide) and recrystallization from acetonitrile to afford the desired product (49 mg, 45%) as a yellow solid: 1H NMR (500 MHz, CDCl3) δ 9.28 (d, J=7.3 Hz, 1H), 8.90 (s, 1H), 8.22 (dd, J=7.8, 1.0 Hz, 1H), 7.72 (dd, J=8.1, 1.0 Hz, 1H), 7.49 (t, J=8.0 Hz, 1H), 4.40-4.30 (m, 1H), 3.58-3.53 (m, 1H), 3.10-3.03 (m, 2H), 3.00 (s, 3H), 2.98-2.94 (m, 2H), 2.90-2.78 (m, 1H), 2.20-2.15 (m, 1H), 2.10-2.00 (m, 1H), 1.85-1.76 (m, 2H), 1.66-1.63 (m, 1H); MS (ESI+) m/z 369 (M+H).
