Lawesson's reagent → 2-[5-(4-chloro-phenyl)-1-(2,4-dichloro-phenyl)-4-methyl-1H-pyrazol-3-yl]-1,5,5-trimethyl-1,5-dihydro-imidazole-4-thione

Participants

Reaction Conditions

Reaction Steps

To a solution of compound 6 (98 mg, 0.22 mmol) in toluene (5 mL) was added Lawesson's reagent (150 mg, 0.37 mmol) in one portion. The resulting mixture was heated at 60° C. for 4 h, then poured into ice water. The resulting mixture was extracted with ethyl acetate (2×30 mL). The combined extracts were washed with water, saturated aqueous sodium bicarbonate, and brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by flash chromatography on silica gel with hexanes/ethyl acetate (7:3) to give the desired thioketone 21 (78 mg, 77%) as a yellow solid. 1H NMR (400 MHz, CDCl3) δ 7.48 (d, 1H), 7.32 (d, 2H), 7.28 (dd, 1H), 7.22 (d, 1H), 7.08 (d, 2H), 3.62 (s, 3H), 2.48 (s, 3H), 1.55 (s, 6H); ESMS m/z: 477.0 (M+1).

Provenance & Evidence