Formaldehyde → (1r)-9-[(3s,4s)-1,3-Dimethylpiperidin-4-Yl]-8-(2-Fluorophenyl)-1-Methyl-3,5-Dihydro[1,2,4]triazino[3,4-C][1,4]benzoxazin-2(1h)-One

Participants

Reaction Steps

A mixture of (R)-7-(2-fluoro-phenyl)-4-methyl-6-((3S,4S)-3-methyl-piperidin-4-yl)-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one hydrochloride acid (3.0 g, 6.74 mmol) and paraformaldehyde (0.506 g, 16.86 mmol) in MeOH (100 mL) and AcOH (10 mL) was stirred at ambient temperature for 2 h. Then, sodium cyanotrihydroborate (0.847 g, 13.49 mmol) was added and the reaction mixture was stirred at ambient temperature for 0.5 h. The reaction mixture was concentrated in vacuo and the residue was purified by column chromatography on basified silica gel (eluting with 10% MeOH in EA) to give (R)-6-((3S,4S)-1,3-dimethyl-piperidin-4-yl)-7-(2-fluoro-phenyl)-4-methyl-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one (2.0 g, 65%) as a white solid. The white solid was stirred in HCl/EtOAc (4 M, 15 mL) for 30 min and the reaction mixture was concentrated in vacuo to give (R)-6-((3S,4S)-1,3-dimethyl-piperidin-4-yl)-7-(2-fluoro-phenyl)-4-methyl-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one hydrochloride acid (1.65 g, 53%) as a white solid. 1H NMR (400 MHz, methanol-d4) δ 7.49-7.40 (m, 1H), 7.33-7.17 (m, 3H), 6.91 (s, 1H), 6.85 (s, 1H), 4.99-4.93 (m, 1H), 4.70-4.65 (m, 2H), 3.60-3.50 (m, 1H), 3.25-3.00 (m, 3H), 2.90-2.85 (m, 1H), 2.80 (s, 3H), 2.55-2.45 (m, 1H), 2.01-1.84 (m, 2H), 1.49 (d, J=6.4 Hz, 3H), 1.00-0.90 (m, 3H). LC/MS (Table 1, Method 4) Rt=1.654 min.; MS m/z: 423 [M+H]+. SFC (Table 1, Method 48), Rt=3.206 min.

Provenance & Evidence