31 Thujopseneの転位

抄録

Treatment of the tricyclic sequiterpene thujopsene (1) with mild acid (0.02M HClO_4 in refluxing 80% aqueous dioxane) gives widdrol (2) as the initial product. Similar treatment of the trans-thujopsene (4) yields epi-widdrol (5) as the initial product. The prolonged heating of the reaction mixture results in the formation of the diene 3 from thujopsene and the diene 6 from the trans-thujopsene. These results indicate that under the mildly acidic conditions, stereochemical integrity of the cyclopropylcarbinyl system is preserved. However, under the strongly acidic conditions, namely 0.02M HClO_4 in refluxing acetic acid, both cis thujopsene and the diene 6 yield a mixture of three hydrocarbons 9, 10 and 11. The structure of the major hydrocarbon 9 was reported previously. The structures of the two minor compounds 10 and 11 are reported here.