Spirovetivane-type sesquiterpenes

However, a dispatch route to the [4.5]spirocyclic sesquiterpenes of the spirovetivane type has been recently reported from the readily available a-siloxycyclopropane-carboxaldehyde, via the stereospecific thermal ring enlargement of a silylated 1-vinylcyclopropanol (202) (equation... 

Irradiation of lumiproducts in aqueous acetic add with UV light above 300 nm brings about photorearrangement to SpirocycHc dienones. This type of transformation was used for the conversion of the nootkatane sesquiterpenes 3,4-dehydronootkatone (153) into the spirovetivane anhydro-P-rotunol (155) and in the synthesis of P-vetivone and 4-epi-P-vetivone from dehydro-P-vetivone. ... 

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