Pyridine → 5-(N-phenylcarbonyl-1,4-dihydro-4-pyridyl)-6-(4-fluorophenyl)-2,3-dihydroimidazo-[2,1-b]thiazole

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Reaction Steps

6-(4-Fluorophenyl)-2,3-dihydroimidazo[2,1-b]thiazole (45.0 g, 0.204 mol) and 55 ml (0.68 mol) of pyridine were dissolved in 500 ml of methylene chloride To this cooled (ice-water bath) solution (10°) was added 91.3 g (0.65 mol) of benzoyl chloride in 100 ml of methylene chloride under a nitrogen atmosphere. During the addition, the reaction pot temperature was not allowed to rise past 10°. After the addition, the desired product precipitated from solution. The addition of the benzoyl chloride solution was continued. The resulting suspension was stirred at ambient temperature for 15 minutes, then heated to reflux for 15 minutes. Thin-layer chromatography (ethyl acetate/hexane/methanol, 15:1:0.1) showed the presence of some starting material. An additional 20 ml of pyridine followed by benzoyl chloride (28 g, 0.2 mol) were added at room temperature The suspension was stirred for an additional 0.5 hour. Analysis did not detect starting material at this time The reaction suspension was filtered. The collected solid was washed with petroleum ether. The solid was vacuum dried to yield 66.8 g (81%) of 5-(N-phenylcarbonyl-1,4-dihydro-4-pyridyl)6-(4-fluorophenyl)-2,3-dihydroimidazo-[2,1-b]thiazole; m.p. 188°-189°.

Provenance & Evidence