The present invention relates to a new method of preparing halogenated styrene compounds of formula (VIII) which are precursors in the process of synthesis of substituted isoxazoline compounds of formula (I) wherein R1 to R5, R8 and R9 are described as in the description. The present invention relates further to the synthesis of compounds of formula (I) starting from acetophenones. The desired styrenes of formula are prepared from the appropriate substituted acetophenone. Asides bromo anilines react with formoxime. Obtained oximes undergo a cycloaddition with the styrenes and give isoxazolines. Compounds of formula (I) can then be prepared in a palladium catalyzed carbonylative amination reaction of the isoxazolines.