Chiral Building Blocks for the Synthesis of Triquinane Sesquiterpenes: Derivatives of 2‐Methylbicyclo[3.3.0]octan‐3‐ol from Catalpol

Abstract

The synthesis of enantiomerically pure triquinane sesquiterpenes is of interest owing to the remarkable biological activity of some of these natural products. The compounds 1–3, which may be prepared from naturally occurring catalpol on a gram scale, are suitable as chiral building blocks. The absolute configuration of (+)‐3, a precursor of (−)‐coriolin, was established by X‐ray structure analysis.

Synthesis of Polyquinane Natural Products: An Update

“…Weinges and co-workers − have restructured the iridoid catalpol ( 271 ) into the diquinane 272 through a series of transformations. Further conversion of the diquinane 272 into Matsumoto's 138k intermediate 273 constituted a formal synthesis of coriolin ( 212 ) (Scheme ).…”

“…Weinges and co-workers [141][142][143] Weinges and co-workers 144,145 have also accomplished the enantioselective syntheses of (-)-coriolin ( 212) and (+)-coriolin-B ( 274) from (S)-carvone, through an extension of their hirsutene strategy (Schemes 65 and 66). The lactone 275 obtained from (S)-carvone was transformed into enyne 276, and the triquinane 277 was assembled employing a samarium iodide-mediated tandem radical cyclization reaction.…”