Molecular rearrangements of superelectrophiles

Abstract

SummarySuperelectrophiles are multiply charged cationic species (dications, trications, etc.) which are characterized by their reactions with weak nucleophiles. These reactive intermediates may also undergo a wide variety of rearrangement-type reactions. Superelectrophilic rearrangements are often driven by charge–charge repulsive effects, as these densely charged ions react so as to maximize the distances between charge centers. These rearrangements involve reaction steps similar to monocationic rearrangements, such as alkyl group shifts, Wagner–Meerwein shifts, hydride shifts, ring opening reactions, and other skeletal rearrangements. This review will describe these types of superelectrophilic reactions.

Tetra- and Pentacationic Electrophiles and Their Chemistry

“…Highly charged organic ions are known to exhibit unusual chemistry, including undergoing reactions with exceptionally weak nucleophiles and participating in deep-seated rearrangements . The chemistry of these ions has been studied both in the gas and solution phases.…”

Superelectrophiles: Recent Advances

“…This includes numerous synthetic methodologies which utilize superelectrophiles, the direct spectroscopic characterization of these ions, and the study through computational and kinetic methods. The chemistry of superelectrophiles was thoroughly reviewed in 2008 [ 3 ], with several focused reviews being published since that time [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. In the following manuscript, recent work in the chemistry of superelectrophiles will be summarized.…”

Triazine-Based Cationic Leaving Group: Synergistic Driving Forces for Rapid Formation of Carbocation Species

“…Successful applications of such LG activation were reported for halogenation , and Friedel–Crafts type reactions, , whose proposed or possible reaction mechanisms involved the formation of cationic LGs (Figure ). However, these reactions were carried out using a large excess (typically the solvent) of a strong acid or a superacid. Furthermore, such cationic LGs only cleaved weak nitrogen–halogen (Cl, Br, or I) bonds or provided carbocations stabilized by heteroatoms such as acylium ions and isocyanate cations (OCNR 2 + ).…”