Diisopropylethylamine → 2-[[4-(2,4-Dichlorophenyl)-1-piperazinyl]methyl]-6-(trifluoromethyl)imidazo[1,2-a]pyridine

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Reaction Steps

A mixture of 2-(chloromethyl)-6-(trifluoromethyl)imidazo[1,2-a]pyridine (0.452 g), 1-(2,4-dichlorophenyl)piperazine (Example 31, Step 1; 0.468 g), diisopropylethylamine (Aldrich; 0.299 g), and THF (4 mL) is stirred at reflux for 21 h. After cooling, the mixture is partitioned between dichloromethane and aq. sodium bicarbonate. The organic layers are dried over sodium sulfate, concentrated, and the residue chromatographed on silica gel using methanol/dichloromethane (2.5/97.5) to give 0.64 g of 2-[[4-(2,4-dichlorophenyl)-1-piperazinyl]methyl]-6-(trifluoromethyl)imidazo[1,2-a]pyridine. The methanesulfonate salt is prepared by dissolving 2-[[4-(2,4-dichlorophenyl)-1-piperazinyl]methyl]-6-(trifluoromethyl)imidazo[1,2-a]pyridine in ethyl acetate/hexane and adding methanesulfonic acid (0.143 g) dissolved in methanol. The mixture is concentrated under reduced pressure and the residue is crystallized from ethyl acetate to give 0.691 g of the title compound; mp 161-162° C.; MS m/z 428; IR (mineral oil) 1162, 1225, 1033, 1130, 1142, 1337 cm-1. 1H NMR (CDCl3) δ 2.78, 3.09, 3.83, 6.96, 7.18, 7.31, 7.35, 7.66, 7.68, 8.47.

Provenance & Evidence