Acetic Anhydride → 1-{2-[4-(2,4-difluorophenoxy)piperidin-1-yl]-3-[(propan-2-yl)amino]-5H,6H,7H,8H-pyrido[3,4-b]pyrazin-6-yl}ethan-1-one

Participants

Reaction Steps

A mixture of 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-3-amine (100 mg, 0.250 mmol), acetic anhydride (0.09 mL, 1.00 mmol) and 10% Pd/C (9.0 mg) in a mixture of dioxane (2.5 mL) and acetone (1.5 mL) was stirred at room temperature for 24 h. Then, 4.0 equivalents of acetic anhydride was added and stirring was continued for 2 days. After filtration, the reaction solution was quenched with saturated NaHCO3 and the aqueous layer was extracted with ethyl acetate (3×5 mL). The combined organic phase was dried with anhydrous Na2SO4 and concentrated under vacuum. Purification by silica gel column chromatography using a 30% to 100% gradient of EtOAc in heptane gave the title compound (57 mg, 51%) as a white solid. 1H NMR (400 MHz, methanol-d4, mixture of rotamers) δ ppm 1.23 (d, J=6.6 Hz, 3.3H), 1.24 (d, J=6.6 Hz, 2.7H), 1.93 (m, 2H), 2.11 (m, 2H), 2.18 (s, 1.3H), 2.20 (s, 1.7H), 2.71 (t, J=6.1 Hz, 0.9H), 2.80 (t, J=6.1 Hz, 1.1H), 2.95 (m, 2H), 3.34 (m, 2H), 3.79 (t, J=5.9 Hz, 1.1H), 3.84 (t, J=6.1 Hz, 0.9H), 4.15 (m, 1H), 4.44 (tt, J=7.5, 3.7 Hz, 1H), 4.53 (s, 0.9H), 4.54 (s, 1.1H), 6.86 (m, 1H), 6.97 (ddd, J=11.2, 8.5, 3.2 Hz, 1H), 7.16 (td, J=9.2, 5.6 Hz, 1H); ESI-MS m/z [M+H]+ 446.00.

Provenance & Evidence