Dioxiranes, MTO/H2O2, and MTO/UHP are becoming increasingly important as ef
ficient and selective oxidants in organic chemistry and numerous publicatio
ns have appeared on each of them. Here we present a comprehensive review, c
omparing the chemistry of these reagents with particular emphasis on the ox
idation of pi bonds, heteroatoms, and sigma bonds. We will discuss structur
al aspects and on this basis, will outline the reactivity and selectivity o
f these oxidants, along, with the mechanistic aspects of the oxygen-transfe
r process.