74. A total synthesis of (±)-isocomene and (±) β-isocomene by an intramolecular ene reaction
    Oppolzer, W.; Bättig, K.; Hudlicky, T.
    Tetrahedron 1981, 37, 4359-4364

The racemic sesquiterpenes isocomene 1 and β-isocomene 22 have been synthesized starting from 1,7-octadien-3-one 10 in a stereoselective manner. In the key step 12 → 13 (Scheme 5) the C-7, C-8-bond was formed by an intramolecular thermal ene reaction. Further transformations of 13 (Scheme 6) involved successively ring contraction 18 → 19, elimination 21 → 22 and olefin isomerization 22 → 1.

DOI : 10.1016/0040-4020(81)80001-4