Total synthesis of avenaol.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28939863.
- Also identified by DOI 10.1038/s41467-017-00792-1 and PMC identifier 5610312.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Avenaol, isolated from the allelopathic plant black oat, was the first C<sub>20</sub> germination stimulant related to strigolactones. Structurally, it consisted of a bicyclo[4.1.0]heptanone skeleton containing a cyclopropane ring bearing three main chains projecting in the same direction (i.e. all-cis-substituted cyclopropane). Herein, we report the total synthesis of avenaol using a robust strategy involving the formation of an all-cis-substituted cyclopropane via an alkylidenecyclopropane. The key factors in the success of this total synthesis include the Rh-catalysed intramolecular cyclopropanation of an allene, an Ir-catalysed stereoselective double-bond isomerisation, and the differentiation of two hydroxymethyl groups via the regioselective formation and oxidation of a tetrahydropyran based on the reactivity of a cyclopropyl group. This strategy effectively avoids the undesired ring opening of the cyclopropane ring and the formation of a caged structure. Furthermore, this study confirms the proposed structure of avenaol, including its unique all-cis-substituted cyclopropane moiety.Avenaol is a potent germination stimulant that can be extracted from black oat. Here, the authors report the total synthesis of avenaol by developing a strategy to access all-cis-substituted cyclopropanes.