Benzoyl isothiocyanate → 4-[(Benzoylamino)thioxomethyl]-4,5-dihydro-7-[3-(trifluoromethyl)phenyl]pyrazolo[1,5-a]pyrimidine-3-carboxamide

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Reaction Steps

To a stirred solution of 3.08 g of 4,5-dihydro-7-[3-(trifluoromethyl)phenyl]pyrazolo[1,5-a]pyrimidine-3-carboxamide (Example 4) in 30 ml of dry acetone, under nitrogen was added 1.5 ml of benzoyl isothiocyanate in 5 ml of dry acetone. The mixture was heated at reflux for 3 hours, then an additional 4.5 ml of benzoyl isothiocyanate was added and the mixture was heated at reflux for 16 hours. The mixture was cooled to room temperature and the solid precipitate that had formed was collected by filtration and washed with ether to give 600 mg of 4-[(benzoylamino)thioxomethyl]-4,5-dihydro-7-[3-(trifluoromethyl)phenyl]pyrazolo[1,5-a]pyrimidine-3-carboxamide, m.p. 210°-212° C. To a stirred mixture of 1.5 g of the preceding product (prepared as described above), 30 ml of N,N-dimethylformamide and 2.0 ml of 1N sodium hydroxide was added 4.0 ml of methyl iodide. This mixture was stirred at room temperature for 3 hours then an additional 1.0 ml of 1N sodium hydroxide and 2.0 ml of methyl iodide were added and stirring was continued. After one hour the addition of 1.0 ml of sodium hydroxide and 2.0 ml of methyl iodide was repeated and stirring was concluded within one hour of this addition. The mixture was mixed with water and the solid precipitate was collected by filtration, washed with water and dried in vacuo to give 1.4 g of 3-(aminocarbonyl)-N-benzoyl-7-[3-(trifluoromethyl)phenyl]pyrazolo[1,5-a]pyrimidine-4(5H)-carboximidothioic acid, methyl ester, m.p. 172°-175° C.

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