4-Methylbicyclo[6.3.0]undecane-2,6-dione, (I), 7-bromo-4-methylbicyclo[6.3.0]undecane-2,6-dione, (II), 7-acetonyl-4-methylbicyclo[6.3.0]undecane-2,6-dione, (III), and 8-methyltricyclo[9.3.0.02,6]tetradec-5-ene-4,10-dione, (IV)

Abstract

The crystal structures of the four title compounds, C 12 H 18 O 2 , (I), C 12 H 17 BrO 2 , (II), C 15 H 22 O 3 , (III), and C 15 H 20 O 2 , (IV), which were obtained during studies of the preparation of C 5 -C 8 -C 5 fused-ring compounds, have been determined. The eight-membered rings in all four compounds take the boat-chair form.