Introduction
<P>Diaryliodonium(III) salts, ArI
+Ar′X
- (Ar,
Ar′ = aryl), are classically
known as trivalent iodine species with two aryl ligands bound to
an iodine atom. These are readily available and easy-to-handle compounds,
and typically form stable crystals. The salts tend to convert into
more stable monovalent iodoarenes under reductive conditions. Due to
the good leaving ability of the iodoarene groups, they are used
as arylating reagents in various reactions, for example, nucleophilic
substitution reactions with various nucleophiles, such as organometallic
agents, enolates,
[
¹]
and heteroatom
nucleophiles,
[
²]
and coupling
reactions using transition-metal catalysts.
[
³]
They
are also valuable as benzyne precursors.
[
4]
Recently,
a number of new C-H bond arylations for providing biaryls
have been reported.
[
5]
In specific
cases, they serve as unique arylating agents under metal-free conditions.
[
6]
</P>
Preparation
<P>Some diaryliodonium(III) salts are commercially available. Non-commercial
salts can be prepared from organometallic compounds by condensation
with hypervalent iodine reagents,
[
7]
or
arenes themselves under heating and/or strong acidic conditions.
[
8]
Recently, versatile direct approaches
have been achieved for preparing diaryliodonium(III) salts.
[
9]
They can be typically isolated
as fine powders by trituration with ether. </P>
