A cis-fused decalone and a bicyclo[4.3.1]-decanone ring system

The crystal structures of (4a alpha,8 alpha,8a alpha)-(+/-)-1-oxoperhydro-8-naphthyl p-bromobenzoate, C17H19BrO3, (2), and (+/-)-endo-5-hydroxy-1-methylbicyclo[4.3.1.]decan-7-one, C11H18O2, (3), were determined in order to ascertain their relative configurations. Compound (2) has two cis-fused six-membered rings which both adopt chair conformations. Compound (3) has a bridged bicyclic ring system consisting of a six- and a seven-membered ring which both adopt chair conformations. Molecules of (3) are linked about inversion centers into dimers by O-H ... O hydrogen bonds [O ... O 2.844 (3) Angstrom] involving the hydroxy and carbonyl groups.