Studies on the Synthesis of Natural Products with Bicyclo[4.4.0]decene Skeleton: Synthesis and Uncatalysed Intramolecular Diels–Alder Reactions of the Decatrienone Substrates
synthesized. Cyclopropanation and subsequent alkylation with sorbyl bromide provided tetrasubstituted siloxycyclopropanes 15 and 16 in good overall efficiency. Their ring cleavage with fluoride reagents gave 1,7,9-decatrienones 5 and 17; the latter was converted into the protected compound 6. The thermal intramolecularDiels–Alderreactions of 5 and 6 were compared with those of related trienones 3 and