4th EucheMs chemistry congress

Poster Session 1
s1087
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - organic chemistry
P - 0 4 5 1
PhotoCAtALySiS with fLAvinS:
hiGh-Power-reduCtionS
C. StAnGLMAir 1
1 Institut für Organische Chemie, Prof. König, Regensburg,
Germany
One of the most famous photoreceptor dyes is riboflavin,
also known as vitamin B , which takes part in a lot of biochemical
2
reactions as coenzyme. [1] Upon irradiation with blue light
(440 nm) their redox power is dramatically increased:
The reduction potential for the two electron reduction is
about -200 mV. [2] This can be used for oxidative chemistry: [3] The
reduced flavin is simply reoxidized by air.
When air is excluded new reduction pathways are enabled:
The reduced flavin can be excited via UV-light which raises the
reduction power enormously. We present our first results
investigating organic reactions with reduced flavins.
Research supports: DFG: GRK 1626 – Chemical
Photocatalysis.
references:
1. A. M. Edwards, in Flavins Photochemistry and
Photobiology, Vol. 6 (Eds.: E. Silva, A. M. Edwards),
The Royal Society of Chemistry, Cambdrige, 2006, pp. 1–11.
2. S. Ghisla, W. C. Kenney, W. R. Knappe, W. McIntire,
T. P. Singer, Biochemistry 1980, 19, 2537–2544.
3. a) R. Lechner, S. Kummel, B. Konig, Photochemical &
photobiological sciences: Official journal of the European
Photochemistry Association and the European Society for
Photobiology 2010, 9, 1367–1377;
b) R. Lechner, B. König, Synthesis2010, 2010, 1712–1718.
Keywords: Photocatalysis; Flavin; Reduction;
4 th EucheMs chemistry congress
P - 0 4 5 2
new C-BridGed n-heteroCyCLeS AS ChirAL
LiGAndS And for CoPPer dioxyGen
CoMPLexeS
M. SteinBACh 1 , r. GÖttLiCh 1 , S. SChindLer 2
1 Justus-Liebig-Universität Gießen, Organische Chemie,
Giessen, Germany
2 Justus-Liebig-Universität Gießen, Anorganische Chemie,
Giessen, Germany
new C-bridged N-heterocycles as chiral ligands: The
concept of C2-symmetry has proved to be invaluable for
asymmetric catalysis. Among the vast number of ligands known,
the most successful ones such as the binaphthyls or the
bisoxazolines contain a C2-symmetry axis, and only a few notable
exceptions such as phosphinooxazolines or ferrocenyl ligands are
equally effective chiral inductors.
As the fact that C2-symmetrical bisoxazolines are excellent
ligands, we were interested in similar methylene-bridged
N-heterocycles like bispiperidine or bistetrahydroquinoline as new
chiral ligands. In comparison to the bisoxazoline nitrogen the
bispiperidine-analogue nitrogen is electronic different due to its
hybridization from which some differences in complexation
properties can be expected. To study these new ligands we
synthesized them, analyzed them and use them to prepare different
complexes. After this they will test as asymmetric catalyst. Results
of these studies will be presented on the poster.
Copper dioxygen complexes with some of these ligands:
Copper is known as active centre of several redox active
metalloproteins. Because of the ability of many copper enzymes
to catalyse selective oxidations with air, one of the goals in
bioinorganic chemistry currently is to model this functionality and
to use such small molecular synthetic copper complexes as
catalysts for selective oxidation reactions in the laboratory and in
industry. To get such a model complex, oxygen is allowed to react
under controlled conditions with a copper(I)-complex of the
N-heterocyclic ligands. To study a couple of these model
complexes, they were synthesized and characterized by using in
this case some similar methylene-bridged N-heterocyclic ligands
like bispiperidine or bisquinoline. Results of these studies will be
presented on the poster.
Keywords: N ligands; Asymmetric catalysis; copper;
O-O activation;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc