反应详情

A solution methanolic hydrogen chloride (approx. 1.6M, 1.5 mL) was added to tert-butyl 5-ethyl-7,8-dihydropyrido[3,4-b]pyrazine-6(5H)-carboxylate (29 mg, 0.11 mmol) dissolved in 0.25 mL of methanol. After 3.5 h, the solution was concentrated under a stream of nitrogen. Methanol (two portions) was added, with evaporation of the solvent after each addition, to give the title compound as a hygroscopic foam. 1H NMR (500 MHz, CD3OD) δ 8.57 (d, 1H, J=3 Hz), 8.54 (d, 1, J=3 Hz), 4.57 (dd, 1H, J=8, 5 Hz), 3.77 (ddd, 1H, J=13, 6, 5 Hz), 3.59 (ddd, 1H, J=10, 6 Hz), 3.37 (ddd, 1H, J=18, 10, 7 Hz), 3.35 (dt, 1H, J=18, 5 Hz), 2.51-2.41 (m, 1H), 2.06-1.96 (m, 1H), 1.18 (t, 3H, J=8 Hz). LC/MS 164 (M+1).

1. concentrationthe solution was concentrated under a stream of nitrogen
2. additionMethanol (two portions) was added, with evaporation of the solvent
3. additionafter each addition