2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → Methyl 5-methyl-2-phenyl-7-p-tolylpyrazolo[1,5-a]pyrimidine-6-carboxylate

Participants

Reaction Steps

To a stirred solution of 4-methylbenzaldehyde (1.2 g, 9.99 mmol), 3-phenyl-1H-pyrazol-5-amine (1.6 g, 9.99 mmol), and methyl 3-oxobutanoate (1.3 g, 10.99 mmol) in THF (80 mL) and heptane (20 mL) was added piperidine (30 mL, 0.303 mmol). The reaction mixture was heated at reflux for 20 h. The solvent was evaporated and the crude material was dissolved in CH2Cl2. DDQ (2041 mg, 8.99 mmol) was added and the mixture was stirred at room temperature for 1 h. The solvent was evaporated. Purification by silica gel chromatography provided the title compound (2.3 g, 64.4%). 1H-NMR (500 MHz, CDCl3) δ ppm 2.47 (3H, s), 2.65 (3H, s), 3.64 (3H, s), 6.93 (1H, s), 7.31-7.47 (5H, m), 7.63 (2H, d, J=7.9 Hz), 7.86-7.99 (2H, m).

Provenance & Evidence