Dimethyl Sulfoxide → ethyl 5-(3-oxopropyl)-1H-pyrazole-3-carboxylate

Participants

Reaction Steps

Dimethylsulfoxide (0.14 mL, 1.9 mmol) was slowly added to a solution of oxalyl chloride (0.137 mg, 1.08 mmol) in CH2Cl2 (1 mL) and THF (1 mL) at −78° C. After stirring for 5 minutes, the solution was added dropwise to a solution of 5-(3-hydroxy-propyl)-1H-pyrazole-3-carboxylic acid ethyl ester (178 mg, 0.898 mmol) in THF (10 mL) at −78° C. The reaction was stirred for 0.5 h and triethylamine (0.64 mL) was added. The suspension was stirred for 40 minutes and was warmed to room temperature. The reaction was diluted with CH2Cl2:hexanes (1:4, 40 mL) and the mixture was washed with 10% aqueous sodium bisulfate (15 mL) followed by water (2×10 mL). The organic solution was dried over MgSO4, filtered, and concentrated to provide the title aldehyde. 1H NMR (400 MHz, CDCl3) δ 9.82 (s, 1H), 6.59 (s, 1H), 4.35 (q, 2H), 3.06 (m, 2H), 2.84 (t, 2H), 1.91 (m, 2H), 1.34 (t, 3H); MS 197 (M+1).

Provenance & Evidence