Direct Fluorination Strategy for the Synthesis of Fluorine‐18 Labeled Oligopeptide—[ 18 F ] ApoPep ‐7

Knowing the extent to which apoptosis occurs will allow us to better understand physiological changes in cells. ApoPep‐1, an oligopeptide with the structure of CQRPPR, is known to be a substance capable of measuring apoptosis well. A method for synthesizing ApoPep‐1 derivative containing fluorine‐18 was studied. The development of a method for labeling fluorine‐18 fluorine on oligopeptide without denaturation of oligopeptide was applied to ApoPep‐1. A derivative of ApoPep‐1, a stable precursor 5  having trimethylammonium nicotinamide functional group was synthesized. The precursor 5 can be labeled at 40–60 °C without denaturing the oligopeptide to provide a new derivative, ApoPep‐7 ( 1 ). Upon radiofluorination of the precursor 5 at 60 °C with large initial activity (11.2 GBq), [ 18 F]ApoPep‐7 ([ 18 F] 1 ) was obtained in a yield of 31% (nondecay corrected, isolated, total preparation time 65 min).