Introduction <P>TEMPO (2,2,6,6-Tetramethyl-1-piperidinyloxy radical), as an oxidizing reagent,
is the most representative member of the generally called nitroxyl radical oxidant
family. They are characterized as weak oxidants that are stable, and soluble in both
polar and apolar solvents. However, the radical can be oxidized to form the corresponding
oxoammonium salt that is capable of oxidizing many organic functional groups. This
oxidized species (Scheme 1) can be generated separately from the reaction mixture
or, more interestingly, in situ, allowing a catalytic cycle.</P><P>Some reviews can
be found in the literature,
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1 ]
but due to the increasing interest for this family of oxidants, new applications
have been published. This Spotlight compiles novel oxidations catalyzed by TEMPO-oxoammonium
salt from 2004 to present.</P>
