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@PHDTHESIS{Thomas:836435,
author = {Thomas, Fabian},
othercontributors = {Herres-Pawlis, Sonja and Schwaneberg, Ulrich},
title = {{C}opper-mediated cross-coupling reactions toward
tandem-catalysis},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2021-11306},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2021},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2022; Dissertation, RWTH Aachen University, 2021},
abstract = {Catalytic transformations are key to the development of
atom efficient processes. An important functional group in
biologically, synthetically and pharmacologically relevant
molecules are amines. The central intermediates in atom
efficient reactions to introduce an amine function are
terminal nitrenes. Terminal nitrene complexes are an elusive
species and rational ligand design helps to understand
connection between the structure and the reactivity.
Therefore, this PhD thesis includes the synthesis of a
library of different bis(pyrazolyl)methane ligands. The aim
was to investigate the influence of the ligand design on the
formation and activity of the generated copper nitrene
complexes. This was achieved by variation of the third N
donor unit of the ligand, whose electronic as well as the
steric properties were varied. By the application of the
nitrene generating agent SPhINTs, six novel copper nitrene
complexes were synthesized at low temperature in
dichloromethane. These nitrene complexes were characterized
by ultra-high resolution cryo ESI mass spectrometry, density
functional theory, UV/Vis and NMR spectroscopy. It was shown
that terminal nitrene complexes are generated as singlet
species in high yields. In addition, the thermal stability
and catalytic activity was investigated. By variation of the
third N donor unit copper nitrene complexes with a high
stability as well as a high cata-lytic activity were
obtained. At room temperature the C–H amination of
different benzylic, alkylic and aromatic substrates and the
aziridination of different styrene derivatives is possible.
Due to the relevance of enantiomeric pure products, also
chiral precursor complexes were used in asymmetric catalytic
reactions and enantiomeric enriched products could be
obtained. To further increase the atom efficiency of the
catalytic amination reaction under avoidance of SPhINTs,
also aromatic azides were used as nitrene generating agents.
A first success was achieved by the combination of benzoyl
azide and electron rich bis(pyrazolyl)methane ligands.
Beside copper(I) complexes also iron(II) complexes were
investigated as precursor complexes to generate nitrene
complexes. Another approach for the development of
environmentally sustainable processes are tandem reactions.
By the combination of two or more catalysts in one process,
a purification of the intermediates is redundant. This leads
to savings in energy and solvent consumption as well as in
the investment costs. Therefore, in the framework of the SFB
985 in the Subproject A1 the aim was to develop a tandem
reaction between a P450 BM3 variant and a copper
bis(pyrazolyl)methane complex. Two possible tandem reactions
were investigated. In the first tandem reaction a
combination of an aromatic hydroxylation of dimethylbenzene
to yield dimethylphenol followed by a copper catalyzed C–O
cross-coupling to a diphenyl ether was planned. Both
reactions could be performed separately, but a combination
was not successful. The second approach is the combination
of a copper catalyzed benzofuran synthesis from iodophenol
and alkyne followed by a hydroxylation of the benzofuran by
a P450 BM3 variant. The combination of both reactions could
be realized in a stepwise reaction and the addition of
EDTA.},
cin = {151910 / 150000},
ddc = {540},
cid = {$I:(DE-82)151910_20150909$ / $I:(DE-82)150000_20140620$},
pnm = {SFB 985 A01 - Mikrogel-gesteuerte chemoenzymatische
Kaskaden unter Verwendung ganzer Zellen (A01) (221465724) /
DFG project 191948804 - SFB 985: Funktionelle Mikrogele und
Mikrogelsysteme (191948804)},
pid = {G:(GEPRIS)221465724 / G:(GEPRIS)191948804},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2021-11306},
url = {https://publications.rwth-aachen.de/record/836435},
}
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