To a solution of 1-(((5S,7S)-3-(5-(2-(2-hydroxyethoxy)propan-2-yl)pyrazin-2-yl)-7-methyl-2-oxo-1-oxa-3-azaspiro[4.5]decan-7-yl)methyl)-1H-benzo[d]imidazole-6-carbonitrile (40 mg, 0.079 mmol) in N,N-Dimethylformamide (DMF) (1 mL) was added sodium hydride (4.76 mg, 0.119 mmol) at RT. After 10 minutes, MeI (0.020 mL, 0.317 mmol) was added and stirred for an hour. To the mixture was added 0.5 mL MeOH and 2 drops 5% AcOH to buffer to pH 10, then filtered and purified by reverse phase HPLC (Waters Sunfire 30×150 mm Acetonitrile:Water 0.1% TFA 50-100%, 50 mL/min, 15 min). The product was free based with PL-HCO3 resin SPE to yield 1-(((5S,7S)-3-(5-(2-(2-methoxyethoxy)propan-2-yl)pyrazin-2-yl)-7-methyl-2-oxo-1-oxa-3-azaspiro[4.5]decan-7-yl)methyl)-1H-benzo[d]imidazole-6-carbonitrile as a white solid (16.5 mg, 39%). 1H NMR (400 MHz, DMSO-d6) δ 9.23 (d, J=1.51 Hz, 1H), 8.57 (d, J=1.51 Hz, 1H), 8.50 (s, 1H), 8.39 (d, J=0.75 Hz, 1H), 7.84 (d, J=8.53 Hz, 1H), 7.60 (dd, J=8.41, 1.38 Hz, 1H), 4.12-4.23 (m, 2H), 3.88 (dd, J=23.09, 10.29 Hz, 2H), 3.43-3.48 (m, 2H), 3.34-3.39 (m, 2H), 3.26 (s, 3H), 2.00 (d, J=13.30 Hz, 1H), 1.89 (d, J=14.31 Hz, 1H), 1.58-1.77 (m, 3H), 1.43-1.56 (m, 8H), 1.30-1.41 (m, 1H), 1.07 (s, 3H). MS (m/z) 519.3 (M+H+).
