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) δ9.82 (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