Micelles generated upon dissolving surfactants in water can be employed as nanovessels for catalytic transformations, in the so-called micellar catalysis methodology. This review is focused on the use of micellar catalysis in the context of the catalytic functionalization of carbon−hydrogen bonds. The micelles accumulate catalyst and reactants in their inner volume in such a high local concentration that kinetics are favored. The consequence is that, in most cases, processes that in conventional organic solvents require high temperatures and long reaction times are achieved in milder conditions when micellar catalysis is employed.
The copper complex Tp(CF3)2,BrCu(NCMe) efficiently catalyses the aziridination of olefins in water using PhI=NTs as the nitrene source, with identical activity than that observed when using dichloromethane as the solvent, under the same experimental conditions. No specific modification of catalyst or substrates are required, nor the presence of additional phase transfer catalyst. Competition experiments and Hammett plots show that the behaviour of the metal centre is the same in both reaction media. This is the first example of a catalytic system employing PhI=NTs for olefin aziridination in water.
The direct oxidation of benzene into phenol using molecular
oxygen
at very mild temperatures can be promoted in the presence of the copper
complex Tp
Br3
Cu(NCMe) in the homogeneous phase in the presence
of ascorbic acid as the source of protons and electrons. The stoichiometric
nature, relative to copper, of this transformation prompted a thorough
DFT study in order to understand the reaction pathway. As a result,
the dinuclear species Tp
Br3
Cu
II
(μ-O
•
)(μ-OH)Cu
II
Tp
Br3
is proposed
as the relevant structure which is responsible for activating the
arene C–H bond leading to phenol formation.
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