Thommen, Christophe. Syntheses of taiwaniaquinoid and icetexane natural products based on biogenetic hypotheses. 2015, PhD Thesis, University of Basel, Faculty of Science.
Restricted to Repository staff only until November 2017.
Official URL: http://edoc.unibas.ch/diss/DissB_11539
A protecting-group-free route to (−)-taiwaniaquinone F based on a Wolff-rearrangement ring contraction and subsequent aromatic oxidation of a sugiol derivative was deviced following a proposed biogenetic pathway. In addition, the first synthesis of (+)-taiwaniaquinol A is reported via short time exposure of (−)-taiwaniaquinone F to sunlight triggering a remote C−H functionalization. The hypothesis that the biogenesis of several methylenedioxy bridged natural products could proceed via similar nonenzymatic mechanisms is presented.
A divergent synthesis of thirteen members of icetexane natural products based on a proposed biogenetic cationic ring expansion of a reduced carnosic acid derivative is described. Among these members, (+)-salvicanol, (−)-cyclocoulterone, (−)-coulterone, (−)-obtusinone D, (−)-obtusinone E, and (−)-euolutchuol E are synthesized for the first time. Following this approach, an additional support to our methylenedioxy biogenetic hypothesis is reported via the photolysis of (+)-komaroviquinone to (−)-cyclocoulterone and (+)-komarovispirone.
Preliminary results towards the mechanistic elucidation of the discovered remote C−H activation are outlined. Photolysis of a model substrate shows the formation of the methylenedioxy moiety for the first time on a non-natural quinone. Preliminary evidence that account for the formation of biradical species are given.
|Advisors:||Gademann, K. and Pfaltz, A.|
|Faculties and Departments:||05 Faculty of Science > Departement Chemie > Chemie > Organische Chemie (Gademann)|
|Bibsysno:||Link to catalogue|
|Number of Pages:||1 Online-Ressource|
|Last Modified:||30 Jun 2016 10:59|
|Deposited On:||27 Jan 2016 15:35|
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