The general procedure for the synthesis of 3-chloro-2-(chloromethyl)-2-methyl-N-phenylpropionamide from pivaloyl chloride and 3,4-dichloroaniline was carried out as follows: firstly, the preparation of N-(3,4-dichlorophenyl)-2,2-dimethylpropionamide was carried out. 3,4-Dichloroaniline (150 g) was dissolved in tert-butyl methyl ether (TBME, 1 L) and the solution was cooled to 10-15 °C. Under vigorous stirring, 30% aqueous sodium hydroxide solution (141 g, 1.14 eq.) was slowly added, followed by dropwise addition of pivaloyl chloride (PivCl, 126 mL) at a rate that controlled the internal temperature to not exceed 30°C. During the dropwise addition, the reaction mixture gradually thickened and precipitated a white solid product. After completion of the dropwise addition (about 10-15 minutes), the reaction mixture was heated to 30-35°C and maintained for 1 hour, followed by cooling to room temperature. The mixture was placed at -5°C overnight and then filtered. The filter cake was washed sequentially with a 90:10 water/methanol mixture (600 mL) and water (900 mL). Finally, it was dried under vacuum to give 195 g (86% yield) of off-white crystalline product.LCMS analysis showed m/z 246 (M-H)+.
