A process for the preparation of a compound of formula (Ia) comprising the following steps: reacting a substituted 2-chloro-5-(trifluoromethyl)benzoyl chloride according to formula with M-SCN; reacting the thus obtained crude 2-chloro-5-(trifluoromethyl)benzoyl isothiocyanate without isolation with a substituted piperazine or homopiperazine of formula, acidifying the thus obtained 2-piperazine or 2-homopiperazine 1,3-benzothiazine-4-one with hydrochloric acid, whereby the compound of formula (Ia) precipitates from the reaction mixture, wherein the reaction is conducted in THF. wherein n is 1 or 2; R 1 is a linear, branched or cyclic C 3-12 alkyl group, a linear, branched or cyclic C 3-12 alkenyl group or a linear or branched C 3-12 alkynyl group, all of which may be substituted with halogen, or wherein X is a linear or branched C 1-6 alkyl group, a linear or branched C 1-6 alkenyl group or a linear or branched C 1-6 alkynyl group; Y is a direct bond, O, S, NH, NMe, NEt, or NPr; Z is a direct bond, or a linear or branched C 1-3 alkyl group; Q is cyclopentyl, cyclohexyl, cycloheptyl, phenyl, or naphtyl, which may be substituted with 1-3 substituents selected from halogen, a linear or branched C 1-3 alkoxy group, a linear or branched C 1-3 alkenyloxy group, a linear or branched C 1-3 alkynyloxy group, mono-, di or trifluoromethyl; M is an alkali metal, or NH 4; R 2 is NO 2, NHOH. reacting a substituted 2-chloro-5-(trifluoromethyl)benzoyl chloride according to formula with M-SCN; reacting the thus obtained crude 2-chloro-5-(trifluoromethyl)benzoyl isothiocyanate without isolation with a substituted piperazine or homopiperazine of formula, acidifying the thus obtained 2-piperazine or 2-homopiperazine 1,3-benzothiazine-4-one with hydrochloric acid, whereby the compound of formula (Ia) precipitates from the reaction mixture, wherein the reaction is conducted in THF. wherein n is 1 or 2; R 1 is a linear, branched or cyclic C 3-12 alkyl group, a linear, branched or cyclic C 3-12 alkenyl group or a linear or branched C 3-12 alkynyl group, all of which may be substituted with halogen, or wherein X is a linear or branched C 1-6 alkyl group, a linear or branched C 1-6 alkenyl group or a linear or branched C 1-6 alkynyl group; Y is a direct bond, O, S, NH, NMe, NEt, or NPr; Z is a direct bond, or a linear or branched C 1-3 alkyl group; Q is cyclopentyl, cyclohexyl, cycloheptyl, phenyl, or naphtyl, which may be substituted with 1-3 substituents selected from halogen, a linear or branched C 1-3 alkoxy group, a linear or branched C 1-3 alkenyloxy group, a linear or branched C 1-3 alkynyloxy group, mono-, di or trifluoromethyl; M is an alkali metal, or NH 4; R 2 is NO 2, NHOH. n is 1 or 2; R 1 is a linear, branched or cyclic C 3-12 alkyl group, a linear, branched or cyclic C 3-12 alkenyl group or a linear or branched C 3-12 alkynyl group, all of which may be substituted with halogen, or wherein X is a linear or branched C 1-6 alkyl group, a linear or branched C 1-6 alkenyl group or a linear or branched C 1-6 alkynyl group; Y is a direct bond, O, S, NH, NMe, NEt, or NPr; Z is a direct bond, or a linear or branched C 1-3 alkyl group; Q is cyclopentyl, cyclohexyl, cycloheptyl, phenyl, or naphtyl, which may be substituted with 1-3 substituents selected from halogen, a linear or branched C 1-3 alkoxy group, a linear or branched C 1-3 alkenyloxy group, a linear or branched C 1-3 alkynyloxy group, mono-, di or trifluoromethyl; M is an alkali metal, or NH 4; R 2 is NO 2, NHOH. X is a linear or branched C 1-6 alkyl group, a linear or branched C 1-6 alkenyl group or a linear or branched C 1-6 alkynyl group; Y is a direct bond, O, S, NH, NMe, NEt, or NPr; Z is a direct bond, or a linear or branched C 1-3 alkyl group; Q is cyclopentyl, cyclohexyl, cycloheptyl, phenyl, or naphtyl, which may be substituted with 1-3 substituents selected from halogen, a linear or branched C 1-3 alkoxy group, a linear or branched C 1-3 alkenyloxy group, a linear or branched C 1-3 alkynyloxy group, mono-, di or trifluoromethyl; M is an alkali metal, or NH 4; R 2 is NO 2, NHOH.