Abstract: The invention relates to a preparation process for the compound (I) or a salt thereof where Q, X*, Y, Z, R, R1, R2 and R3 are as defined in claim 1, which comprises a) monoesterifying a compound (II) where Hal=a halogen atom, giving (III), b) either b1) ammonolysing and phosgenating this compound to give (V) or b2) converting this compound with cyanate into (V) and c) converting the resulting compound (V) with the aminoheterocycle H2N-Het (Het=heterocycle as in (I)) into the compound (I) or a salt thereof. Some compounds (II) and some intermediates (VIII), stabilized with N-heteroaromatic compounds, of the compounds (V) are novel. The compounds (II) can be obtained from the corresponding sulfobenzoic acids by reaction with acid halides of sulfur or phosphorus in nonpolar organic solvents.