Ring opening and rearrangement reactions of tricyclo [ 2,5]nonan-9-one

Ingbert Braun, Florian Rudroff, Marko D. Mihovilovic, Thorsten Bach

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


A general concept is introduced to synthesize bicyclo[4.2.0]octanes by a sequence of intramolecular coppers-catalyzed [2+2] photocycloaddition and subsequent fragmentation reactions. The concept was tested by subjecting the photochemically accessible tricyclo[,5]nonan-9-one to four different ring-opening or rearrangement reactions, which allowed for the formation of functionalized bicyclo[4.2.0]octanes by cleavage of the carbonyl bridge. All four methods investigated, Haller-Bauer cleavage, the Schmidt reaction, Baeyer-Villiger oxidation, and rhodium(II)-catalyzed rearrangement were applicable to tricyclo[,5]nonan-9-one, but they differed with regard to enantioselectivity. Enzymatic Baeyer-Villiger oxidation was the most successful of these methods, also more successful than metal-catalyzed Baeyer-Villiger oxidation, providing access to enantiomerically enriched lactones, for example in 72% yield and 95% ee. The second-most successful method was with a commercially available rhodium catalyst, which effected ring enlargement of tricyclo[,5]nonan-9-one to its homologue in good overall yield and modest enantioselectivity (up to 24% ee).

Original languageEnglish
Pages (from-to)3896-3906
Number of pages11
Issue number24
StatePublished - 17 Dec 2007


  • Cycloadditions
  • Ketones
  • Lactones
  • Photochemistry
  • Ring opening
  • Stereoselective synthesis


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