Iodonium nitrate in pyridine–chloroform at room temperature undergoes preferential electrophilic addition to certain olefinic alcohols to form (i) hydroxyiodoalkyl nitrates and (ii) hydroxyiodoalkylpyridinium nitrates. Parallel reactions in sym-collidine–chloroform gave three-, four-, and five-membered cyclic ethers as well as products of type (i). Introduction of a hydroxy-function stabilises the intermediate iodonium ion leading to an increase in the product ratio (ii): (i) relative to the additions to alkenes of comparable structure. The trans stereospecific addition of iodonium nitrate to cyclohex-2-en-1-ol indicates that the iodonium ion is formed cis to the hydroxy-group during the reaction.
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Diner et al. (1971) studied this question.