Synthesis
Step 2: Synthesis of 1-(2-amino-5-chlorophenyl)-2,2,2-trifluoroethanone hydrochloride from 4-chloro-2-bromophenylneopentanamide. A small amount of iodine pellets was added to a mixture containing magnesium shavings (1 equiv.) and 2 volumes of tetrahydrofuran (THF) to initiate the reaction at room temperature. Subsequently, the starting material (4-chloro-2-bromophenyl) pivalamide (1 g) was added and waited for the reaction to initiate. After the reaction started, the feedstock dissolved in 1 volume of THF was added dropwise. After dropwise addition, lithium chloride (0.25 mmol) was added to the reaction mixture and stirred at room temperature for about 6 hours. The reaction mixture was cooled to -15 °C and ethyl trifluoroacetate (1.4 mmol) was added. The temperature of the reaction mixture was raised to 20 °C and kept for about 30 min, after which the reaction was quenched with ammonium chloride solution. The reaction mixture was extracted with methyl tert-butyl ether (MTBE), the organic layers were combined and concentrated under reduced pressure. Acetic acid (4 vol) and hydrochloric acid (2 vol) were added to the resulting crude product. The reaction mixture was slowly heated to 75 °C and kept at this temperature for about 4 hours. Upon completion of the reaction, the mixture was cooled to 0-5 °C and kept for 2 h. The mixture was filtered and washed with 1 volume of ethyl acetate to give 4-chloro-2-(trifluoroacetyl)aniline hydrochloride in 70% yield.
