m-Chloroperbenzoic acid → 2-[4,4-bis(trifluoromethyl)-2-(4-fluorophenyl)-4,5-dihydro-1H-imidazol-5-ylidene]-1-(4-fluorophenyl)-1-ethanone

Participants

Reaction Steps

To a solution of α,α-bis(trifluoromethyl)-4,5-bis(4-fluorophenyl)-1H-pyrrole-2-methanamine (5.0 g, 0.012 mole) in chloroform (100 mL) was added portionwise, m-chloroperbenzoic acid (MCPBA, 4.09 g, 0.024 mole). The reaction mixture was refluxed under nitrogen for one hour. Then additional MCPBA (2.05 g, 0.012 mole) was added and the mixture was refluxed for 1 hour. The solution was cooled to room temperature and poured into saturated sodium bicarbonate (200 ml). The organic layer was washed successively with saturated sodium bicarbonate solution, 10% sodium sulfite solution, water, and saturated sodium chloride solution, dried over magnesium sulfate and evaporated under vacuum. The residue was columned in silica gel eluted with hexane-ethyl acetate 20:1 then 10:1 to give the 2-[4,4-bis(trifluoromethyl)-2-(4-fluorophenyl)-4,5-dihydro-1H-imidazol-5-ylidene]-1-(4-fluorophenyl)-1-ethanone (1.02 g, 20%) as a yellow solid: mp 121°-123°; MS m/e 435 (M+ +H); 1H NMR (CDCl3 /TMS) δ 6.73(s,1H,C=CH), 7.17-7.30(m,4H,Harom), 8.00-8.10(m,4H,Harom), 11.80(s,1H,NH). Another product, N[2-(4-fluorophenyl)-4,5-dihydro-1-methyl-5,5-bis(trifluoromethyl)-1H-imidazol-5-yl]-N-methylacetamide (2.09 g, 56%) was also isolated as a solid: mp 114°-115°; MS m/e 437 (M+ +H); 1H NMR (CDCl3 /TMS) δ 2.57(s,2H,NH2), 3.87(s,1H,NH), 6.77(s,1H,C=CH), 6.90-7.03(m,4H,Harom), 7.23-7.40(m, 2H,Harom), 7.15-7.17(m,2H,Harom).

Provenance & Evidence