Trichloroacetyl chloride → 4-(4-Bromo-2-fluorobenzyl)-3-n-butyl-1-(2-chloro-5-nitrophenyl)-1H-pyrazole-5-carbonitrile

Participants

Reaction Conditions

Reaction Steps

A mixture of 600 mg (1.18 mmol) of 4-(4-bromo-2-fluorobenzyl)-3-n-butyl-1-(2-chloro-5-nitrophenyl)-1H-pyrazole-5-carboxamide (from Step E), 330 μL (238 mg, 2.35 mmol) of triethylamine, and 7 mL of methylene chloride was cooled to 0° C. and treated with 145 μL of trichloroacetyl chloride. The mixture was stirred under N2 and allowed to warm to room temperature. After 3 hours, the mixture was concentrated to dryness. The orange residue was triturated with ether. The insoluble material was removed by filtration. The filtrate was washed with 0.2N HCl followed by 0.25N NaOH. The organic layer, after being dried over Na2SO4, was filtered and concentrated. The orange residual oil was flash chromatographed on silica gel (elution with 4:1 and then 3:1 hexane-EtOAc) to give 399 mg (69%) of the title compound as a yellow oil; nearly homogeneous by TLC in 3:1 hexane-EtOAc; mass spectrum (FAB) m/e 491, 493 (M+1)+. 200 MHz 1H NMR (CDCl3) δ0.91 (t, J=7.1 Hz, 3H), 1.36 (m, 2H), 1.61 (m, 2H, partially obscured by H2O peak), 2.61 (t, J=7.7 Hz, 2H), 3.97 (s, 2H), 7.07 (dd, J=8, 8 Hz, 1H), 7.26-7.31 (m, 2H), 7.78 (d, J=8.8 Hz, 1H), 8.31-8.39 (m, 2H).

Provenance & Evidence