Selectivity in the halohydroxylation of cyclohexadienediols

The halohydroxylation of a number of cyclohexadienediol derivatives has been investigated. The selectivity of the reaction as a function of the type of substituent on the diene, protecting group of the diol functionality, halonium donor, medium polarity, and temperature is described. Best selectivity is obtained for iodohydrin formation. The course of the reaction for these dienic systems is heavily dependent on steric factors.