Reaction of iodonium nitrate with some olefinic alcohols

Abstract

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.