A bioinspired approach to Tri-nor-guaianes. Synthesis of (-)-clavukerin A
A bioinspired approach to tri-nor-guaianes by degradation of the C-7 side chain of related guaia-11-enes is described. In this approach (-)-clavukerin A (1) is obtained by selective ozonolysis-Criegge rearrangement of (+)-1α H,7αff,10αH-guaia-4,11-dien-3-one (4) to afford 7β-hydroxy and 7β-acetoxy tri-nor-guaiane derivatives 6 and 7, respectively, which after elimination and deoxygenation give the title compound. The starting guaiadienone is readly obtained from commercially available santonin or (+)-dihydrocarvone.
Blay, Gonzalo,Garcia, Begona,Molina, Eva,Pedro, Jose R.
8-Endo cyclization of (alkoxycarbonyl)methyl radicals: Stereoselective synthesis of (-)-clavukerin A and (-)-11-hydroxyguaiene
(-)-Clavukerin A was synthesized from (+)-limonene oxide via 8-endo radical cyclization. (-)-11-Hydroxyguaiene was also synthesized, but its spectroscopic data did not match with those reported for the natural product.
Enantioselective Synthesis of Guaianolides in the Osmitopsin Family by Domino Metathesis
Relay metathesis enabled an improved access from (S)-citronellal to the marine trisnorguaiane (-)-clavukerin A. This hydroazulene was applied as an advantageously functionalized building block for the asymmetric synthesis of the sesquiterpene lactone osmitopsin and the proposed structure of 4,5-epoxyosmitopsin using a chemo-, regio-, and diastereoselective diepoxide opening as the key step.
Barthel, André,Kaden, Felix,J?ger, Anne,Metz, Peter
supporting information
p. 3298 - 3301
(2016/07/13)
Synthesis of sesquiterpene-inspired derivatives designed for covalent binding and their inhibition of the NF-κB pathway
A significant portion of bioactive secondary metabolites are endowed with reactive functionalities that can engage in covalent interactions with their target. Sesquiterpene lactones in particular are rich in Michael acceptors that react with cysteines. Several polycyclic scaffolds derived from total synthesis or readily available polycyclic terpenes were used as the starting point in the synthesis of a library aiming to project mildly reactive functionalities (Michael acceptors or chloroacetates) with diverse geometries. Screening of the library for inhibition of the NF-κB pathway revealed several potent inhibitors that are chemically readily accessible.
Duplan, Vincent,Serba, Christelle,Garcia, Jose,Valot, Gaelle,Barluenga, Sofia,Hoerle, Melanie,Cuendet, Muriel,Winssinger, Nicolas
p. 370 - 375
(2014/01/06)
A concise catalytic route to the marine sesquiterpenoids (-)-clavukerin A and (-)-isoclavukerin A
Using a combined organocatalytic/metal-catalyzed strategy, the enantiopure title hydroazulenes were prepared in only four steps from (S)- and (R)-citronellal, respectively. A catalyst-controlled diastereoselective Michael addition of these aldehydes to methyl vinyl ketone followed by chemoselective dibromoolefination and one-pot Wittig olefination/alkyne formation afforded the key dienynes that underwent regioselective domino metathesis to yield the target natural products. A combination of an organocatalytic Michael addition and a ruthenium-catalyzed dienyne metathesis allowed efficient access to the enantiopure title hydroazulenes from (S)- and (R)-citronellal, respectively, in only four steps.
Knueppel, Stephan,Rogachev, Victor O.,Metz, Peter
supporting information; experimental part
p. 6145 - 6148
(2010/12/29)
Chiral Synthesis of a Trinorguaiane Sesquiterpene, Clavukerin A
An enantiospecific synthesis of clavukerin A, a novel trinorguaiane sesquiterpene, was accomplished starting from (-)-carvone.
Honda, Toshio,Ishige, Hirohide,Nagase, Hiromasa
p. 3305 - 3310
(2007/10/02)
Total Synthesis of Clavukerin A and Its Epimer
Enantioselective synthesis of clavukerin A and its epimer was carried out.By the comparison of the spectral data and specific rotations of synthesized and natural ones, two trinorsesquiterpens isolated from Clavulia and Cespitularia species are confirmed