The trinorguaiane sesquiterpenes clavukerin A 1., and 1 and isoclavukerin 2 3 are marine natural products that have been isolated from the Okinawan soft coral Clavularia koellikeri during a search for biologically active compounds from marine sources. So far three total syntheses of isoclavukerin 3., 4., and and five total syntheses of clavukerin A have been described, 4., , , 5., , and including three enantiocontrolled routes and two for the racemate. ... Honda et al., 5c Asaoka et al. ...