Triethylamine → 2-[5-(4-chloro-phenyl)-1-(2,4-dichloro-phenyl)-4-methyl-1H-pyrazol-3-yl]-5,5-dimethyl-3,5-dihydro-imidazol-4-one

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Reaction Steps

To a solution of 4a (1.01 g, 2.62 mmol) in toluene (30 mL) at 0° C. were sequentially added DMF (0.2 mL) and oxalyl chloride (1.48 g, 11.66 mmol) dropwise. The mixture was allowed to warm to room temperature and stirred for 2 h, then transferred slowly to a mixture of 5i (0.56 g, 4.07 mmol) and triethylamine (0.42 g, 4.20 mmol) in THF (120 mL) at 0° C. After the mixture was warmed and stirred at room temperature for 15 h, water was added and the resulting mixture was extracted with ethyl acetate (2×30 mL). The combined extracts were washed with brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The crude amide (1.02 g) thus obtained was treated with a solution of POCl3 (1.25 g, 8.15 mmol) in dichloromethane (25 mL) at 80° C. for 4 h. The mixture was concentrated and poured into ice water. The resulting mixture was extracted with ethyl acetate (2×50 mL). The combined extracts were washed with brine, dried over anhydrous sodium sulfate, filtered, and concentrated. Purification of the residue by flash chromatography on silica gel with ethyl acetate/hexanes (7:3) afforded 23 (0.62 g, 53%) as a white solid. 1H NMR (400 MHz, CDCl3) δ 7.43 (br s, 1H), 7.32˜7.27 (m, 4H), 7.05 (d, 2H), 7.00 (br s, 1H), 2.38 (s, 3H), 1.81 (s, 6H); ESMS m/z: 447.0 (M+1).

Provenance & Evidence