In the present work, we investigated the fluoro-for-chloro substitution in position 5 of the benzoxazole ring of JH112 (Figure ; compound 1e) and the influence of alternative heteroarenes on OX1R affinity and subtype selectivity (Figure ; compound 1f and heteroarene derivatives 1a-d), taking into account the accessibility of 18 F-labeled derivatives by copper-mediated aromatic 18 F-fluorination. We identified the 6-fluorobenzothiazole derivative 1f as a ligand with subnanomolar OX1R affinity and retained OX1R selectivity, whose 18 F-labeled analog was investigated in vitro and in preliminary in vivo experiments.