De Boeck B, Harrington-Frost NM, Pattenden G. Tandem cyclisations involving α-ketenyl alkyl radicals. New syntheses of the natural triquinanes pentalenene and modhephene.
Org Biomol Chem 2005;
3:340-7. [PMID:
15632977 DOI:
10.1039/b413817c]
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Abstract
New synthetic approaches to the angular and propellane sesquiterpene triquinanes (+/-)-pentalenene 2 and (+/-)-modhephene 3, respectively, are described. The syntheses are based on tandem cyclisations involving alpha-ketene alkyl radical intermediates produced from alpha,beta-unsaturated acyl radical species, as highlighted in Schemes 2 and 4.
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