Feature article in JOC!

The chemiluminescence efficiency of catalyzed 1,2-dioxetanone decomposition is determined by steric effects

Fernando Heering BartoloniMarcelo Almeida de OliveiraLuiz Francisco M.L. CiscatoFelipe Alberto AugustoErick Leite Bastos,* and Wilhelm Josef Baader*
J. Org. Chem.DOI: 10.1021/acs.joc.5b00515

Abstract

The chemiluminescent decomposition of 1,2-dioxetanones (α-peroxylactones), catalyzed by an appropriate fluorescent activator, is an important simple model for efficient bioluminescent transformations. In this work, we report experimental data on the catalyzed decomposition of two spiro-substituted 1,2-dioxetanone derivatives, which support the occurrence of an intermolecular electron transfer from the activator to the peroxide. The low efficiency of the studied systems is associated with sterical hindrance during the chemiexcitation sequence, rationalized using the concept of supermolecule formation between the peroxide and the catalyst. This approach explains the difference in the chemiexcitation efficiencies in the decomposition of four-membered cyclic peroxide derivatives: 1,2-dioxetanes, 1,2-dioxetanones and 1,2-dioxetanedione (the intermediate in the peroxyoxalate reaction), which are the most important model compounds for excited state formation in chemiluminescence and bioluminescence processes.