Flobufen is prepared by a Friedel-Crafts reaction of 2,4-difluorobiphenyl (II) with methylsuccinic anhydride (I). Methylsuccinic acid (III) can be obtained by hydrolysis and subsequent decarboxylation of ethyl 2-cyano-3-methylsuccinate (IV), which is prepared by condensation of ethyl ester of 2-bromopropionic acid (V) with ethyl cyanoacetate. 2,4-Difluorobiphenyl (II) can be obtained by a Gomberg reaction of 2,4-difluorophenyl diazonium salt (VI) [prepared from difluoroaniline (VII)] with toluene in the presence of Cu.