The role of radicals in metal-assisted oxygenation reactions.
Angew Chem Int Ed Engl, 42 (48):
5932--5954 (December 2003)DOI: 10.1002/anie.200300578
Abstract
The oxo-functionalization of organic substrates with the aid of metal
oxo moieties is of fundamental importance not only in nature but
also in academic and industrial research. Nevertheless the corresponding
reaction mechanisms remain among the most enigmatic in chemistry
and few of them are understood in detail. Recent research efforts
have resulted in significantly improved information: in the cases
of many oxygenation reactions evidence has been provided for the
occurrence radical intermediates, even though the high selectivity
observed suggests to a different mechanism. Examples stem from various
areas of chemistry and include processes involving molecular metal
oxo complexes, gas-phase and matrix-isolated species, metalloenzymes,
and solid-state oxide surfaces. This review treats this seemingly
wide variety of systems with the aim of providing an overview of
common reactivity patterns and principles, as well as open problems.