N,N-Diethylaniline → 3-Bromo-2-(4-chloro-2-fluorophenyl)-2,4,5,6-tetrahydrocyclopenta[c]pyrazole

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Reaction Steps

A mixture of 6.3 parts of 2-(4-chloro-2-fluorophenyl)-1,4,5,6-tetrahydrocyclopentapyrazol-3(2H)-one, 7.9 parts of phosphorous oxybromide, 3.7 parts of N,N-diethylaniline and 10 parts of N,N-dimethylformamide was refluxed 24 hours and poured into 100 parts of water. After neutralizing with 50% aqueous sodium hydroxide solution, the mixture was extracted twice with 100 parts of diethyl ether. The ether extract was dried over anhydrous magnesium sulfate and the solvent was removed under a reduced pressure of 100 mm. Hg at ambient temperature. The crude product was recrystallized from ethanol-water to yield 2.1 parts of 3-bromo-2-(4-chloro-2-fluorophenyl)-2,4,5,6-tetrahydrocyclopentapyrazole melting at 106°-110°.

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