A solution of 3-[7-(3,5-dimethylisoxazol-4-yl)-2-oxo-1,2,4,5-tetrahydroimidazo[1,5,4-de][1,4]benzoxazin-4-yl]pyridine-2-carboxylic acid (10.0 mg, 0.026 mmol) in N,N-dimethylformamide (0.50 mL) was treated with methylammonium chloride (4.30 mg, 0.064 mmol) followed by N,N-diisopropylethylamine (22.2 μL, 0.127 mmol) and stirred at room temperature for 5 min. The reaction mixture was treated with benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate [Aldrich #: 226084](16.9 mg, 0.038 mmol) and stirred at room temperature for 1 h. Purification by preparative LCMS (XBridge C18 column, eluting with a gradient of acetonitrile/water containing 0.1% ammonium hydroxide, at flow rate of 60 mL/min) gave the desired product (5 mg, 48%) as a racemic mixture. 1H NMR (300 MHz, DMSO-d6) δ 9.06-8.91 (m, 1H), 8.57 (d, J=3.6 Hz, 1H), 7.49 (dd, J=8.1, 4.6 Hz, 1H), 7.10 (d, J=7.4 Hz, 1H), 6.93-6.74 (m, 2H), 6.47 (s, 1H), 4.65-4.37 (m, 2H), 2.62 (d, J=10.1 Hz, 6H), 2.24 (s, 1.5H), 2.07 (s, 1.5H); LCMS calculated for C21H20N5O4 (M+H)+: m/z=406.1. found: 406.1.
