Dimethylformamide → ethyl 5-formyl-1-(4-methoxybenzyl)-1H-pyrazole-4-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

According to Scheme 17 Step 1: Butyl lithium 2.5 M (16.9 mmol, 8.45 mL) was added to a solution of diisopropylamine (16.9 mmol, 2.37 mL) in THF (10 mL) at −78° C. and the reaction mixture was stirred at −78° C. for 5 minutes and then at room temperature. To the resulting LDA solution was added at −78° C. a solution of ethyl 1-(4-methoxybenzyl)-1H-pyrazole-4-carboxylate (7.68 mmol, 2 g) in THF (30 mL) and the reaction mixture was stirred for 5 minutes at −78° C. N,N-Dimethylformamide (61.5 mmol, 4.73 mL) was added and then the reaction mixture was stirred at room temperature. The reaction mixture was diluted with AcOEt and was washed with a saturated aqueous solution of NH4Cl. The combined organic phases were dried over MgSO4, were filtered and were evaporated. The crude mixture was purified by flash chromatography over silica gel using cyclohexane/AcOEt (100:0 to 80:20) as eluent to yield ethyl 5-formyl-1-(4-methoxybenzyl)-1H-pyrazole-4-carboxylate (4.62 mmol, 1.33 g, 60%).

Herkunft & Nachweise