Potassium tert-butoxide → 1H-Pyrrole-3-carbonitrile, 4-(4-chlorophenyl)-5-(trifluoromethyl)-

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Reaction Steps

Potassium-t-butoxide (2.46 g, 0.022 mol) is added in portions to a solution of 3-(p-chlorophenyl)-1,1,1-trifluoro-2-propanone oxime, (E)-, or (Z)-(4.75 g, 0.02 mol) in tetrahydrofuran (20 mL) at such a rate that the temperature if maintained at 25°-30° C. (ice-water bath). The resulting solution is stirred for 15 minutes and then added dropwise to a solution of β-chloroacrylonitrile (1.75 g, 0.02 mol) in tetrahydrofuran (15 mL) at 15°-10° C. over 1/2 hour. The ice bath is removed and the reaction mixture is stirred for 1 hour, diluted with water, made acidic with a small amount of dilute HCl and extracted with ether. The combined ether extracts are washed with water and brine and dried (Na2SO4). Concentration in vacuo gives an oil which is dissolved in methylene chloride and filtered through a bed of flash column silica gel (30 mL size) and washed with an ethyl acetate/methylene chloride mixture (1:1). The filtrate is evaporated and the residual semi-solid is crystallized from methylene chloride/hexanes to give the title product as a yellow solid (2.10 g): mp 162.5°-164.0° C. IR (Nujol) 3200, 2250 cm-1, 1H NMR (DMSO-d6) δ7.42, 7.56 (AB, JAB =8.3 Hz, ArH), 8.03 (s, 1H, 2H); 19F NMR δ-51.2; 13C NMR δ94.2 (C-3), 115.0 (CN), 116.6 (q, 2JCF =38.3 Hz, C-5), 120.6 (q, 1JCF =268.7 Hz, CF3), 127.0 (q, 3JCF =3.5 Hz, C-4), 128.6 (C-2') 129.1 (C-1'), 129.7 (C-2), 130.8 (C-3'), 133.4 (C-4').

Provenance & Evidence