New total synthesis of (±)-herbertene, (±)-β-herbertenol and (±)-herbertenediol

The total syntheses of the herbertane sesquiterpenes (±)-herbertene (1), (±)-β-herbertenol (2) and (±)-herbertenediol (5) have been successfully accomplished involving copper-catalysed conjugate addition of Grignard reagents to unsaturated compounds and α,α-dimethylation of primary esters as key reactions.