Enantiospecific First Total Synthesis and Assignment of Absolute Configuration of the Sesquiterpene (−)-Cucumin H

The first total synthesis of the sesquiterpene (−)-cucumin H, a linear triquinane isolated from Macrocystidia cucumis, has been accomplished starting from (R)-limonene employing two different cyclopentannulation methodologies, which in addition to confirming the structure also established the absolute configuration of the natural product.