Kinetics and energetics of the addition of iodonium nitrate to unsaturated systems

Abstract

The stereochemistry of the products of addition of iodonium nitrate to a series of cycloalk-2-en-1-01s indicates that the intermediate iodonium ion is formed cis to the neighbouring hydroxyl in the case of five-, six-, and seven-membered cyclic alkenols and trans to the hydroxyl In the case of cycloct-2-en-1-01, The rates and Arrhenius parameters for the second-order additions of iodonium nitrate to these and other unsaturated substrates have been determined. An n-hydroxy group enhances the rate of addition over the corresponding alkene when the iodonium ion is formed cis to the hydroxyl and has the opposite effect when it is formed trans to the hydroxyl. This evidence for neighbouring hydroxyl group participation in additions of iodoniurn nitrate is in contrast to the known chemistry of iodine isocyanate and iodine azide. The effects of structural changes of the substrate on the kinetic and energetic parameters in iodonium nitrate additions are discussed and compared with those of other pseudo-halogens. [Traduit par le journal] 1Inkrodustion pseudohalogens in that in this reagent the iodine In previous papers we have explored the is complexed to two pyridine groups through chemical behavior of iodonium nitrate, par-nitrogen (1, 2). The effect of this complexation ticularly in electrophilic additions to a wide range may alter its relative electrophilicity compared to of unsaturated substrates (1-4). Hodonium nitrate other iodine containing pseudohalogens such as (generated by the reaction of iodine chloride iodine isocyanate, iodine chloride, and iodine with silver nitrate in chloroform-pyridine) like azide depending on the electronic and steric ,C---C\ also observed that iodonium nitrate in both P q~~d~n e 1

Counterion influence on the N–I–N halogen bond

“…[Bis(pyridine)iodine] + complexes are common synthetic reagents for halogenation and oxidation, [95][96][97][98][99][100][101][102][103] with Barluenga's reagent being the most famous one. 36,41 The latter was recently shown to exhibit a counterion dependent order-disorder phase transition in the solid state 13 and has received increasing attention for applications in parallel synthesis 104 and protein chemistry, 69 for example.…”