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Synfacts 2024; 20(11): 1127
DOI: 10.1055/s-0043-1775142
Synthesis of Natural Products

Total Synthesis of (±)-11-O-Debenzoyltashironin

Contributor(s):
Erick M. Carreira
,
Tristano C. Martini
Cook SP, Polara A, Danishefsky SJ. * Columbia University, New York, USA
The Total Synthesis of (±)-11-O-Debenzoyltashironin.

J. Am. Chem. Soc. 2006;
128: 16440-16441
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Key words

(±)-11-O-debenzoyltashironin - sesquiterpene - Stille cross-coupling - oxidative dearomatization - transannular Diels–Alder reaction

Significance

Danishefsky and co-workers report the first total synthesis of the sesquiterpene (±)-11-O-debenzoyltashironin. The natural product, isolated from the pericaps of Illicium merrillianum, exhibits potent neurotrophic activity in fetal-rat cortical neurons. The synthesis relies in a remarkable tandem oxidative dearomatization/ transannular Diels–Alder reaction, which rapidly assembles the tetracyclic core of the target molecule.


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Comment

The synthesis commenced with elaboration of 2-methylresorcinol (A) into aromatic ­bromide B. Stille cross-coupling of B with vinyl ­stannane C followed by oxidation returned aldehyde D, which was subjected to alkyne addition mediated by Zn(Et)2/Ti(Oi-Pr)4. The resulting propargylic ­alcohol was mesylated and substituted by SN2' ­nucleophilic methylation furnishing key allene G. Oxidation with PIDA followed by microwave irradiation of G triggered the tandem oxidative dearomatization/Diels–Alder reaction yielding tetracycle I. The tertiary alcohol in the natural product was installed via epoxide J.


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Publication History

Article published online:
16 October 2024

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