High-Yielding Automated Convergent Synthesis of No-Carrier-Added [ 11 C- Carbonyl ]-Labeled Amino Acids Using the Strecker Reaction.

A new variant of the Strecker synthesis using no-carrier-added [ ¹¹ C]cyanide for the synthesis of radiolabeled amino acids is described. The protocol is fully automated using a radiochemistry synthesis module and applied to the production of a number of new PET radiotracers. [ ¹¹ C- Carbonyl ]sarcosine, [ ¹¹ C- carbonyl ]methionine, [ ¹¹ C- carbonyl ]- N -phenylglycine, and [ ¹¹ C- carbonyl ]glycine are all synthesized in moderate to good radiochemical yields. The synthesis of [ ¹¹ C- carbonyl ]sarcosine has been validated for production of doses for clinical use, and preliminary evaluation of the new radiotracer in PC3 tumor-bearing mice is also reported.