The synthesis of Ambra oxide related compounds starting from (+)-larixol. Part 3

(+)-Larixol can be easily transformed into intermediates with an hydroxyl group at C(6), a Δ7 double bond and a substituted side chain at C(9) with a second hydroxyl group. Abstraction of the allylic hydroxyl group at C(6), followed by interception of the resulting mesomeric carbocation at C(8) by the hydroxyl group in the side chain, allows the synthesis of some C(13) modified Δ6-tricyclic tetrahydropyranyl ethers (Δ6-Ambra oxides). The formation of Δ6,8-dienes proves to be a seriously competing reaction.