A method for producing a radiofluorinated compound having an aromatic or heteroaromatic ring carrying [18F] fluorine as first substituent, a bonding unit, which can bind to a peptide or peptide mimetic, and a spacer group connected via bond A1 to the bonding unit and via bond A2 to the ring, wherein the bonding unit has second substituent(s) —OH, —CONH, and/or —COOH. The steps include (a) providing a precursor having the ring carrying a substituent Y, bonding unit with the second substituent(s), and spacer group, wherein substituent Y is —N+(R1R2R3), —NO2, —Cl, —Br, —F, or —I, and R1, R2, and R3 are independently C1-C6 alkyl; and (b) reacting the precursor with a [18F] fluoride anion in the presence of an activation salt to the radiofluorinated compound, which has a cation N+(R4R5R6R7) with R4, R5, R6, and R7 being independently C1-C6 alkyl, wherein the substituent Y is replaced by [18F] fluoride.