4-(Trifluoromethyl)benzoyl chloride → 1-Methyl-5-(p-trifluoromethylbenzoyl)-pyrrole-2-acetonitrile

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Reaction Steps

A solution of 14.4 g. (0.12 mole) of 1-methylpyrrole-2-acetonitrile and 25 g. (0.12 mole) of p-trifluoromethylbenzoyl chloride in 120 ml. methylene chloride is chilled to -25° C. (external bath). Then 14 ml. (0.12 mole) stannic chloride is added dropwise over a half hour. The resultant suspension is permitted to come to room temperature and poured into ice-dilute hydrochloric acid. The aqueous phase is separated and washed successively with N,N-dimethyl-1,3-propane-diamine, 3N hydrochloric acid and a saturated solution of sodium chloride. The solvent is evaporated, and the product is isolated from the residual oil by column chromatography using acid-washed alumina. The solvents hexane, benzene, and ether are used as eluents. The first compound-bearing fraction not giving a positive Enrlich's test (in benzene) is collected. The solvent is evaporated and the resultant solid, 1-methyl-5-(p-trifluoromethylbenzoyl)-pyrrole-2-acetonitrile, in purified by recrystallization from isopropanol, m.p. 95-97.5° C.

Provenance & Evidence