4th EucheMs chemistry congress

Monday, 27-Aug 2012
s757
chem. Listy 106, s587–s1425 (2012)
organic Chemistry, Polymers – i
organometallic Chemistry, catalysis, new frontiers – ii
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deSiGn And CAtALytiC ACtivity of nitroxide
orGAnoCAtALyStS
A. SzPiLMAn 1
1 Technion Israel Institute of Technology, Schulich Faculty of
Chemistry, Haifa, Israel
Nitroxides are intriguing compounds with many potential
applications such as polymerization initiators, radical trapping
reagents and catalysts for the oxidation of alcohols. Key to their
catalytic reactivity is the integrity of the nitroxyl/oxoammonium
functionality under the reaction conditions. However, this stability
can normally only be insured by attaching two alkyl groups on
either side of the nitroxide. Nitroxides bearing alfa hydrogen,
although potentially more reactive catalysts undergo rapid
decomposition to the corresponding catalytically inactive nitrones.
We have developed a new design concept to ensure the
stability of nitroxides with alfa hydrogens. We will present the
first C2-symmetric nitroxide prepared according to this concept.
This compound is able to efficiently oxidize even highly sterically
alcohols at low catalyst loadings (2 mol%). We will discuss the
properties of these compounds and their potential applications in
asymmetric catalysis.
organometallic Chemistry, catalysis, new frontiers – iii
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weLL-defined CAtioniC GALLiuM(iii)
CoMPLexeS: A new tooL in orGAniC SyntheSiS
v. GAndon 1
1 Université Paris-sud, Institut de chimie moléculaire et des
matériaux d’Orsay, Orsay Cedex, France
Well-defined neutral and cationic gallium(III) halide
complexes have been synthesized and evaluated in catalysis. Both
the (NHC)GaX /AgSbF catalytic mixture and isolated
3 6
(NHC)GaX 2
4 th EucheMs chemistry congress
+ species function as exquisite π-Lewis acids in
typical GaX -catalyzed reactions. The cationic complexes are
3
more active than GaX and yet more resistant to hydrolysis, which
3
allows lower catalytic loadings and faster reactions. Reactions that
are not catalyzed by standard π-acids such as gold or platinum
complexes are now possible with these new gallium species.
Keywords: cycloisomerization; gallium; homogeneous
catalysis; Lewis acids; N-heterocyclic carbenes;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc