Synthesis and radioiodination of some 9-aminoacridine derivatives

Derivatives of 9-aminoacridine, namely N-[ω-(acridin-9-yl-amino) alkyl]-3-(trimethylstannyl)benzamides (1), where the alkyl group is propyl (1a) and octyl (1b), and 2-(acridin-9-ylamino)-3-(4-hydroxyphenyl)propionic acid (2), have been synthesized with the aim to use them as precursors in the syntheses of radiolabeled DNA intercalators for biological experiments. It was observed that compounds 1a and 1b can exist in two isomeric forms at room temperature. Radioiodination of the two benzamides 1a and 1b was carried out with the Auger-emitting nuclide ¹²⁵I by exchange of the trimethylstannyl group. The optimal conditions for radioiodination of the octyl derivative 1b were established and the labeling yield was found to be as high as 92%, according to TLC analysis in model experiments. Purification of the radioiodinated products gave radiochemical yields of 56% for the propyl and 74% for the octyl compound. The amino acid 2 was directly labeled with ¹²⁵I at the ortho position to the hydroxyl group by taking advantage of the activated ring. The experiment afforded a very high labeling yield (92%).