Dimethylformamide → 956723-13-0

Participants

Reaction Conditions

Reaction Steps

To a stirred, pre-cooled solution of 1-phenethyl-1H-pyrazole (1.10 g, 6.39 mmol) in THF (30 mL) at −78° C., was added dropwise n-BuLi (4.8 mL, 7.66 mmol; 1.6 M in hexane) at such a rate that the internal temperature stayed below −70° C. The mixture was stirred at −78° C. for 1.5 h, during which time the anion precipitated out as a yellow solid. Then DMF (1.25 mL, 15.97 mmol) was added neat and dropwise, and the reaction stirred at −78° C. for 90 min when TLC indicated the reaction was not progressing any further. It was quenched with NH4Cl solution (10 mL), allowed to warm to rt and extracted with EtOAc (4×50 mL). The combined organic extracts were washed with water, brine, dried (Na2SO4), filtered and concentrated. Purification by flash chromatography (Isco CombiFlash) 0-10% EtOAc/heptane provided 2-phenethyl-2H-pyrazole-3-carbaldehyde (540 mg, 43%). 1H NMR (400 MHz, CDCl3) δ ppm 3.09-3.15 (m, 2H), 4.74-4.80 (m, 2H), 6.88 (d, J=2.10 Hz, 1H), 7.16-7.20 (m, 2H), 7.20-7.32 (m, 3H), 7.58 (d, J=2.01 Hz, 1H), 9.77 (s, 1H); LCMS-MS (ESI+) 200.88 (M+H).

Provenance & Evidence