High diastereoselectivity in Claisen rearrangement in a sterically congested cyclopentane system. Total synthesis of (±)-β-necrodol

Total synthesis of the monoterpene β-necrodol has been accomplished. The key step involves an ortho-ester Claisen rearrangement in a highly sterically congested cyclopentane derivative resulting in a high level of 1,3-trans diastereoselection. A novel photo-induced decarboxylation of the obtained γ,δ-unsaturated acid afforded β-necrodol.