Halogenation-driven 'cut-to-fuse' method reshapes esters into coumaranones

Researchers at Ritsumeikan University and collaborators have developed a mild chemical strategy that edits molecular skeletons by first cleaving bonds via halogenation and then reconnecting fragments into a new ring structure. The method converts hydroxycoumarins into coumaranones by deleting a carbonyl group, overcoming the usual resistance of ester bonds to cleavage. Published in JACS Au, the approach offers a practical route for pharmaceutical-oriented molecular restructuring.

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The team's initial fluorine-based attempts caused hydroxycoumarins to break apart into separate fragments, but switching to chlorine via N-chlorosuccinimide redirected the process entirely. A chlorinated intermediate formed and underwent decarbonylative reconstruction, yielding coumar