Studies on 5-8 Fused Ring Compounds. IV. The Syntheses of 5-8-5 Fused Ring Compounds and the Conformations of Their Eight-Membered Rings

Abstract

Abstract The isomers, cis-cisoid-cis- and cis-transoid-cis-tricyclo[9.3.0.04,8]tetradecane-2,9-dione (2 and 3) and cis-cisoid-cis-tricyclo[9.3.0.03,7]tetradecane-2,9-dione (4) were synthesized by the photocycloaddition of bicyclo[4.3.0]nonane-2,4-dione (1) to cyclopentene. X-Ray analyses of those compounds revealed that the conformations of the eight-membered rings are twist-boat in 2, chair in 3, and boat–chair form in 4.