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Terpenes and Terpene Derivatives, XXX. Isolation and Synthesis of Isohumbertiol, the First Naturally Occurring Sesquiterpene Alcohol with a Humbertiane Skeleton

1992; Wiley; Volume: 1992; Issue: 12 Linguagem: Inglês

10.1002/jlac.1992199201218

0170-2041

Peter Weyerstahl, Christian Fynbo Christiansen, Helga Marschall,

Plant Toxicity and Pharmacological Properties

Abstract From Vassoura oil ( Baccharis dracunculifolia DC.) the four isomeric isohumbertiols A – D ( 7 – 10 ), the first naturally occurring sesquiterpene alcohols with a humbertiane skeleton could be isolated and assigned unambiguously by establishing a correlation with the known cabreuva oxides A – D ( 3 – 6 ). Reaction of the ketone (+)‐ 16 with vinylmagnesium bromide gave a mixture of the isohumbertiols B and D [(+)‐ 8 and ent ‐ 10 ]. Treatment of 8/10 with SnCl 4 furnished the tetraline derivative 18 , whereas with hydrochloric acid the cabreuva oxides B and D ( 4 and 6 ) were obtained.