Bromination of methylene groups exocyclic to cyclohexyl systems can afford, besides the expected trans-dibromo products, considerable quantities of a tribromide. For example, simple bromination of 4-t-butyl-1-methylidene-cyclohexane affords c. 20% yield of (r-1, t-2, c-4)-1,2-dibromo-1-bromomethyl-4-t-butylcyclohexane.