Synthesis of AB Ring Model System of TaxolviaAllylation of 8-Membered Ring Compound and Intramolecular Aldol Condensation

1-t-Butyldimethylsiloxy-8,11,11-trimethylbicyclo[5.3.1]undec-7-en-9-one (2) has been synthesized via intramolecular aldol condensation of the precursor 3 by combined use of lithium diisopropylamide (LDA) and CeCl3. The dicarbonyl compound 3 was prepared by allylation of 8-membered ring ketone 6b.