Potassium Carbonate → 1,3-dimethyl-5-(4-methylpiperazin-1-yl)-1H-pyrazole-4-carbaldehyde

Participants

Reaction Steps

To a solution of 5-chloro-1,3-dimethyl-1H-pyrazole-4-carbaldehyde (25.4 g, 0.16 mol) in HMPA (25 mL) and water (25 mL) was added 1-methylpiperazine (40 g, 0.4 mol, 2.5 equiv), and the mixture was heated at 120–125° C. for 25 h. When the reaction was completed, the reaction mixture was poured into water (500 mL), and potassium carbonate was added to make the medium strongly alkaline. The mixture was extracted with dichloromethane (5×100 mL). The combined organic extracts were washed twice with water and dried with sodium sulfate, and the solvent evaporated. The residue was purified chromatographically on silica gel with gradient elution from dichloromethane to methanol, affording 10.2 g (29%) of the title product. Satisfactory C,H,N-analysis was obtained. 1H NMR (400 MHz, DMSO-d6): δ 2.23 (s, 3H), 2.26 (s, 3H), 2.44 (m, 4H), 3.16 (m, 4H), 3.59 (s, 3H), 9.88 (s, 1H). LC-MS (API-ES) calcd for C11H18N4O: 222.15, found (M+H+): 223.1 m/z.

Provenance & Evidence