Hydrochloric Acid → 6-Chloro-5-fluoroindolin-2-one

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Reaction Steps

A 26.63 g. sample of the N-(2-chloro)-2-chloro-4-fluoroaniline was thoroughly mixed with 64 g. of anhydrous aluminum chloride, and the mixture was heated at 210°-230° C. for 8.5 hours. The reaction mixture was then poured onto a mixture of ice an 1N hydrochloric acid, with stirring. Stirring was continued for 30 minutes, and then the solid was collected by filtration (22.0 g.). The solid was dissolved in 1:1 ethyl acetate-hexane and chromatographed on 800 g. of silica gel. Elution of the column, followed by evaporation of the fractions, produced 11.7 g. of the N-(2-chloroacetyl)-3-chloro-4-fluoroaniline, followed by 3.0 g. of 6-chloro-5-fluorine-2-oxindole. The latter material was recrystallized from toluene to give 1.70 g. (7% yield) of the title compound, m.p. 196°-206° C. Analysis by NMR spectroscopy indicated that the product was contaminated by some 4-chloro-5-fluorooxindole. A second crop weighing 0.8 g. was obtained.

Provenance & Evidence