5-Bromo-spiro-[1,2-dioxane-4,4'-tricyclo-[4.3.1.1]undeca-ne]-3'-ol.

The title compound, C(14)H(21)BrO(3), comprises a seven- (C(7)) and three six-membered (1 × O(2)C(4) and 2 × C(6)) rings, and each adopts a conformation based on a chair. Stability to the mol-ecular structure is afforded by an intra-molecular O-H⋯Br hydrogen bond. In the crystal structure, mol-ecules are arranged into a helical supra-molecular chain along the b axis, linked by C-H⋯O inter-actions, where the O-atom acceptor is one of the dioxane O atoms. The crystal studied was found to be a racemic twin. The major component was present 94% of the time.