Co-Catalyzed Peroxidation of Cyclic -Dicarbonyls

A Co-catalyzed peroxidation of cyclic beta-dicarbonyls (cyclic 1,3-diketones, 4-hydroxy-2(5H)-furanones and Meldrum's acids) with TBHP has been disclosed. A series of the alkylperoxy derivatives of 4-hydroxy-2(5H)-furanones and Meldrum's acids were synthesized in moderate to good yields (13-86 %). The functionalization of 4-hydroxy-2(5H)-furanones by the tBuOO group was performed with high selectivity in the presence of the cocktail of reactive oxidizing species, including metal and radical intermediates. The key species in the peroxidation process are probably the tert-butylperoxy radical or its Co(III) complex, which are generated from the Co(II)/TBHP system. Cycle cleavage, which would be expected for cyclic beta-dicarbonyls based on previous reports, was observed to a large extent only for cyclic 1,3-diketones. The reactivity of cyclic beta-dicarbonyls (cyclic beta-diketones, 4-hydroxy-2(5H)-furanones, and Meldrum's acids) towards metal/hydroperoxide system was disclosed. An efficient method for the peroxidation of 4-hydroxy-2(5H)-furanones and Meldrum's acids with TBHP has been developed using Co2+ salt as a catalyst. Cycle cleavage, expected from previous reports for cyclic beta-dicarbonyls, was observed only for cyclic 1,3-diketones. Overall, this work extends the understanding of metal-catalyzed peroxidation towards different structural motifs. image