Scheme 1. Synthesis of the fluorescent dibenzodiazepinone-type MR ligands 15–20, labelled with TAMRA (15, 20), BODIPY630/650 (16), pyrylium/pyridinium dye Py-1 (17, 19) or Py-5 (18). Reagents and conditions: (a): DIPEA, DMF, rt, 2 h, 31% (15), 23% (16), 16% (17), 23% (19), 66% (20); (b) triethylamine, DMF, rt, 2 h, 28% (18).
