Hyperiones A and B are enantiomeric norligans that were first isolated in 2010 from the leaves of the Chinese herb Hypericum chinense, which belongs to the genus Hypericaceae; commonly referred to as St. John’s Wort.

David Barker and co-workers from the University of Auckland, New Zealand, have designed a method for synthesising (−)-hyperione A and (−)-hyperione B by using a single chiral precursor, derived from an Evans anti-aldol reaction, in ten steps. The successful synthesis of the targets has added crucial evidence for the correct structures of the natural products, questions about which have remained since the first attempts to synthesise the hyperiones were made. The evidence, in the form of optical rotation data, suggests that the structures of the natural isolates may have to be revised.

The team has demonstrated that other norligan analogues can be synthesised by using their method, and it is hoped that that this route offers a more efficient pathway to produce norligans in the future.

• Total Synthesis of ent-Hyperione A and ent-Hyperione B,
  Nina Duhamel, Claire E. Rye, David Barker,
  Asian J. Org. Chem. 2013, 2, 491–493.
  DOI: 10.1002/ajoc.201300086