Total syntheses of (±)-β-pinguisene and (±)-pinguisenol

Important ring-skeletons, such as hydroazulene 2 , bicyclooctane 4 , or hydrindanone 12 can be easily obtained by Amberlyst 15 (A 15) catalyzed cyclizations of allyl- and propargylsilanes. The total syntheses of (±)-β-pinguisene 5 and (±)-pinguisenol 6 have been achieved by propargylsilane-terminated cyclizations of enone 11 as the key step. Compound 12 was transformed in a straight forward way to provide β-pinguisene 5 and pinguisenol 6 .