Synthesis of bicyclic dioxetanes tethering a fluororescer through an ω-carbamoyl-substituted linker and their high-performance chemiluminescence in an aqueous system

Bicyclic dioxetanes 3 and 4 tethering a fluorescein or 4-(benzothiazol-2-yl)-3-hydroxyphenyl moiety through a linker were synthesized by the use of dihydrofuran-intermediate 5 or its advanced intermediate 6. These dioxetanes underwent base-induced decomposition to effectively give light due to intramolecular energy-transfer from an excited oxidobenzoate to a tethered fluorophore. Although the chemiluminescence efficiency ΦCL values for 3 and 4 were only ca. 2-fold greater than that for parent 2 in a TBAF/acetonitrile system, these values were 30-550-fold greater than that for 2 in a NaOH/H2O system. Such marked increase of ΦCL was hardly observed by the simple addition of 25 or 26 as a model of a tethered fluorescer.