Boron trifluoride etherate → HCID 13050566, compound

Participants

Reaction Steps

A mixture of 124 g (0.484 mole) of 4,5-bis(4-fluorophenyl)imidazole, 84 g (1.0 mole) dihydropyran, 20 g boron trifluoride etherate and 1 l ethyl acetate was heated at reflux over a weekend. Analysis by TLC (ethyl acetate) showed the presence of some unchanged starting material, so 20 g (~0.24 mole) of dihydropyran and 5 g boron trifluoride etherate was added and heating was continued overnight. The mixture was then diluted with 1 l ether and washed with 10% sodium bicarbonate solution (3×1 l). The organic layer was dried and concentrated on a rotary evaporator. The residual solid was recrystallized from methylcyclohexane (removing some insoluble starting material by filtration) to give 140.2 g (85%) of 4,5-bis(4-fluorophenyl)-1-(2-tetrahydropyranyl)imidazole as a white solid, mp 149°-152°. F-NMR indicated purity ~95%. A smaller run was chromatographed to give pure material mp 158°-9°. IR: 3.25μ (=CH); 3.38, 3.49μ (sat. CH); 6.22, 6.28, 6.41, 6.60, 6.69μ (C=C and/or C=N); 8.20μ (CF); 9μ region (C--O--C). H-NMR: m(1.4-2.1 δ, 6H); m (3.4 δ, 1H); m (4.0 δ, 1H); m (4.7 δ, 1H); m (6.6-7.5 δ, 8H); s (7.8 δ, 1H). F-NMR: two multiplets (112.4 25 δ and 116.5 δ, each decouples to a singlet).

Provenance & Evidence