Triethylamine → 1-(3-Benzyloxyphenyl)-3-tert-butylimidazo[1,5-a]pyrazin-8-ylamine

Participants

Reaction Steps

N-[(3-Benzyloxyphenyl)-(3-chloropyrazin-2-yl)-methyl]-2,2-dimethylpropionamide: To a solution of the crude C-(3-benzyloxyphenyl)-C-(3-chloropyrazin-2-yl)-methylamine (444 mg, max. 1.36 mmol) in CH2Cl2 (5 mL), cooled by ice/water, are added NEt3 (210 μL, 152 mg, 1.51 mmol), DMAP (8 mg, 0.07 mmol), and pivaloyl chloride (185 μL, 181 mg, 1.50 mmol), then the cooling bath is removed, and the reaction solution is stirred at ambient temperature for 4.5 h. More pivaloyl chloride (90 μL, 88 mg, 0.73 mmol) and NEt3 (100 μL, 73 mg, 0.72 mmol) are added and also after further 2.5 h, and the solution is stirred overnight at ambient temperature. The reaction mixture is taken up in EtOAc (35 mL), washed with diluted HCl, water, NaHCO3 sol., and brine, dried over MgSO4, filtered, and concentrated in vacuo. The crude material is chromatographed on silica gel [Jones Flashmaster, 50 g/150 mL cartridge, eluting with hexanes:EtOAc 10:1 (1-17)→3:1 (18-41)→2:1 (42-56)], yielding the title compound as orange oil; 1H NMR (CDCl3, 400 MHz) δ 1.21 (s, 9H), 5.03 (s, 2H), 6.50 (d, J=8.0 Hz, 1H), 6.86-6.90 (m, 1H), 6.93-6.97 (m, 2H), 7.23 (t, J=7.8 Hz, 1H), 7.29-7.43 (m, 6H), 8.32 (d, J=2.4 Hz, 2H), 8.50 (d, J=2.4 Hz, 1H). MS (ES+): m/z 410.1/412.1 (100/36) [MH+], 309.1/311.1 (32/12) [MH+-tBuCONH2].

Provenance & Evidence