A mixture of 1-(6-(1-methyl-1H-pyrazol-4-yl)benzo[d]thiazol-2-yl)azetidin-3-one (Reference Example 4, 17 mg, 0.06 mmol), pyrrolidine (0.015 mL, 0.18 mmol), and a catalytic amount of acetic acid (0.005 mL) in toluene (0.4 mL) was stirred at room temperature for 5 minutes, then sodium triacetoxyborohydride (38 mg, 0.18 mmol) was added. The reaction mixture was stirred at room temperature overnight. The reaction mixture was then quenched with 1 M aqueous K3PO4 (0.4 mL), and extracted twice with ethyl acetate. The combined organic layers were dried over sodium sulfate and concentrated. The crude product was purified by silica gel chromatography (60:40 dichloromethane/acetonitrile to 56:40:4 dichloromethane/acetonitrile/methanol) to give 6-(1-methyl-1H-pyrazol-4-yl)-2-(3-(pyrrolidin-1-yl)azetidin-1-yl)benzo[d]thiazole. 1H NMR (300 MHz, CD3OD) δ ppm 1.84-1.90 (m, 4H), 2.59-2.66 (m, 4H), 3.59-3.68 (m, 1H), 3.92 (s, 3H), 4.06-4.12 (m, 2H), 4.26-4.32 (m, 2H), 7.45 (dd, J=1, 8 Hz, 1H), 7.50 (dd, J=2, 8 Hz, 1H), 7.79 (d, J=1 Hz, 1H), 7.85 (d, J=2 Hz, 1H), 7.92 (d, J=1 Hz, 1H); MS (ESI) m/z 340 (M+H)+.
