A novel process for preparing the compounds of the formula I where: n is 0, 1 or 2; R1, R2 are C1-C6-alkyl; R3, R4, R5 are hydrogen or C1-C6-alkyl, or R4 and R5 together form a bond; R6 is Cl, Br, which comprises a synthesis sequence starting from 1,2-dialkylbenzenes of the formula II with subsequent halogenation to give 3,6-dihalo-1,2-dialkylbenzenes, haloalkylation to give benzyl bromides, oxidation to give benzaldehydes, oximation, reaction with alkenes to give isoxazoles, conversion into thioethers and, if appropriate, oxidation to give sulfenyl or sulfonyl derivatives of the formula I.