Regioselective bromination of tetronic acid-derived γ-lactones and metal-catalyzed post-functionalization: an efficient access to new γ-ylidenetetronate derivatives

The synthesis of several methyl and benzyl γ-ylidenetetronates was accomplished and the bromination reactions of these derivatives, using bromine or N-bromosuccinimide (NBS), were found to occur under mild conditions. Several new brominated γ-unsaturated lactones derived from tetronic acid were prepared in moderate to good yields, with some of them characterized by single crystal X-ray diffraction. A preliminary reactivity study of two bromine-derived γ-benzylidene methyl tetronates, in Sonogashira cross-coupling reactions, with also preparation of 1,2,3-triazole-derived γ-benzylidene methyl tetronate under Cu(I)-catalyzed condition, was performed with an indication that these brominated γ-benzylidene tetronates are useful platforms to produce diversified γ-lactones.