Iodonium nitrate in chloroform-pyridine at room temperature undergoes a trans stereospecific electrophilic addition to alkenes to form (i) iodoaliphatic nitrate esters,(ii) iodoalkane pyridinium nitrates, or (iii) alkene pyridinium iodides depending on the substrate. The addition is sensitive to steric hindrance effects and anti-Markovnikov addition is commonly encountered. In similar additions to conjugated dienes 1, 2-additions in a ...