Acetic Anhydride → 1-(3-(cyclobutylamino)-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)-7,8-dihydropyrido[3,4-b]pyrazin-6(5H)-yl)ethanone

Participants

Reaction Conditions

Reaction Steps

To N-cyclobutyl-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine (0.500 g, 1.218 mmol) in acetone (25 mL) and dioxane (25 mL) was added palladium, 10 wt % on activated carbon (0.052 g, 0.487 mmol) as a slurry in dioxane (3 mL) under nitrogen. Next, acetic anhydride (1.144 mL, 12.18 mmol) was added at 23° C. The mixture was stirred under hydrogen at 310 kPa for 50 hr at 45° C. The crude mixture was filtered through Celite™, rinsed with dioxane, and concentrated via rotary evaporation. The crude material was purified via medium pressure chromatography using a 10% to 100% gradient eluant of EtOAc in heptanes on an NH 60 μM size 60 column (Shoko Scientific Purif-Pack™) to give the title compound 1-(3-(cyclobutylamino)-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)-7,8-dihydropyrido[3,4-b]pyrazin-6(5H)-yl)ethanone (284 mg, 51.1%) as a yellow foam. 1H NMR (500 MHz, DMSO-d6, mixture of rotamers) δ ppm 1.56-1.72 (m, 2H), 1.97-2.06 (m, 2H), 2.07 (s, 1.3H), 2.08 (s, 1.7H), 2.18-2.27 (m, 2H), 2.52-2.66 (m, 4.9H), 2.69 (t, J=5.9 Hz, 1.1H), 2.99 (br s, 4H), 3.59 (s, 2H), 3.69 (dt, J=11.5, 6.0 Hz, 2H), 4.27-4.46 (m, 3H), 5.89 (d, J=7.3 Hz, 0.4H), 5.93 (d, J=7.8 Hz, 0.6H), 7.02-7.13 (m, 1H), 7.17-7.27 (m, 1H), 7.41-7.55 (m, 1H); ESI-MS m/z [M+H]+ 457.0.

Provenance & Evidence