新しい骨格変換法の開発とテルペノイド合成への応用

抄録

Novel skeletal transformations of bicyclo [4.2.0] octan-2-ones via 8-membered-ring carbocation intermediates have been developed. The acid-catalyzed rearrangement of 5, 6-disubstituted bicyclooctanones is a highly-efficient method for synthesis of polycyclopentanoids such as diquinanes, angularly-fused triquinanes, spiro-annulated triquinanes, and tetraquinanes. The reaction of 5-6-4 fused ring ketones with acid in acid anhydride is a unique method for construction of 8-membered-ring compounds such as bicyclo [6.3.0] undecanes. The acid-catalyzed rearrangement of 6-substituted bicyclooctanones provides an excellent method for synthesis of bicyclo [4.2.1] nonanes. Utility of our novel method has been demonstrated by synthetic studies of terpenoids such as 5-oxosilphiperfol-6-ene, silphiperfol-6-ene, 3-oxosilphinene, and mediterraneol B.