Reactions of Some Bicycloalkyl Iodides with Bromine

Article abstract of DOI:10.1021/jo00135a007

The reactions of normally unreactive bicyclic iodides such as 1- and 7-iodonorbornane with bromine has been found to occur readily with the formation of the corresponding bromide.The reaction involves the formation of the complex RI*X2 as an intermediate and is accelerated by polar solvents.The reaction of 1-iodobicyclo<2.1.1>hexane with bromine led to rearranged products, showing that a cationic intermediate is involved.The data indicate that the IBr2^- ion is one of the best of the known leaving groups for S_N1 or S_N2 reactions.The observation of a rapid reaction of the bridgehead bicyclo<2.2.2>octyl iodides with bromine has led to a reexamination of the reaction of 1,4-diiodobicyclo<2.2.2>octane with butyllithium.The previous report of the formation and trapping of the <2.2.2>propellane in this reaction was found to be incorrect.