Dimethyl Sulfoxide → 5-Methyl-1-(4-methylbenzyl)-1H-pyrazole-3-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of oxalyl chloride (1.69 mL, 19.4 mmol) in dichloromethane (10 mL) at −78° C. was added DMSO (3.45 mL, 18.6 mmol) as a solution in dichloromethane (5 mL) dropwise over a period of 10 min. To this reaction mixture was added [5-methyl-1-(4-methylbenzyl)-1H-pyrazol-3-yl]methanol (Step 1, 4.2 g, 19.42 mmol) as a solution in dichloromethane (50 mL) dropwise over a period of 30 min. The mixture was stirred at −78° C. for 1.5 h. and triethylamine (13.5 mL, 97.1 mmol) in dichloromethane (5 mL) was then added dropwise. The resultant mixture was warmed to 0° C. and stirred for 20 min. To this mixture was added water (25 mL) dropwise, followed by dichloromethane (100 mL). The organic layer was separated, and the aqueous layer was extracted with dichloromethane (1×100 mL). The combined organic extracts were washed with HCl (0.5 M aq., 1×50 mL), dried (Na2SO4), and filtered. The organic layer was passed through a small plug of silica gel using ethyl acetate as eluent, and was concentrated under reduced pressure to afford the title compound as a yellow oil (3.7 g, 89%): 1H NMR (300 MHz, DMSO-d6) δ 9.80 (s, 1H), 7.12 (d, 2H), 7.03 (d, 2H), 6.57 (s, 1H), 5.36 (s, 2H), 2.25 (s, 3H), 2.23 (s, 3H): ES-MS m/z 214.98, HPLC RT (Method A) 3.33 min.

Provenance & Evidence