Famesene synthesis

Several natural products (Scheme 60) have been synthesized in vitro via singlet oxygen ene reactions. For example, clavukerin C was prepared202 in racemic form, in a biomimetic synthesis by Kim and Pak, whereas a-famesene hydroperoxide was obtained203 starting from geraniol. 

Aside from the stoichiometric construction of steroidal side chains by the reaction of alkenylzirconium derivatives with steroidal 7r-allylpalladiums, a one-pot synthesis of a-famesene and its 6Z-isomer from generanyl and neryl chlorides, respectively, reported in 1981 appears to be the first example of natural product syntheses via Pd-catalyzed allylation (Scheme 21). 

Following a very satisfactory synthesis of a-famesene via alkenyl-aUyl cou-pling[i74] example of natural product syntheses of this class, some other... 

The hydrozirconation proceeds smoothly with zirconium catalyst. The subsequent Negishi coupling with allyl chlorides enable the synthesis of skipped (nonconjugated) dienes such as famesenes (Scheme 5-105). ... 

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