4th EucheMs chemistry congress

Monday, 27-Aug 2012
s754
chem. Listy 106, s587–s1425 (2012)
organic Chemistry, Polymers – i
organometallic Chemistry, catalysis, new frontiers – i
o - 0 7 2
PoLyfunCtionAL orGAnoMetALLiCS AS Key
interMediAteS in orGAniC SyntheSiS
P. KnoCheL 1
1 Ludwig-Maximilians-Universität, Department Chemie,
München, Germany
Polyfunctional zinc, magnesium, and lithium
organometallics are key organometallic intermediates in organic
synthesis and new advances in the preparation and synthetic use
of these organometallics will be presented. Thus, a stereoselective
preparation of cyclohexyl-lithiums and related reagents by
using a novel iodine-lithium exchange will be shown. The
configurational stability of secondary cycloalkyl lithium,
magnesium, and zinc reagents will be discussed as well as the
stereochemistry (retention or inversion) of their reactions with
various organic electrophiles. By using sterically hindered
magnesium amides, selective directed metalations of
functionalized aromatics and heterocycles will be performed. Also
the preparation of air-stable zinc aryl and heteroaryl zinc
pivalates will be shown. Applications of these new reagents in
palladium-catalyzed cross-couplings as well as in the construction
of heterocyclic scaffolds will be reported.
Keywords: Cross-coupling; Lithium; Magnesium; Palladium;
Zinc;
4 th EucheMs chemistry congress
organometallic Chemistry, catalysis, new frontiers – i
o - 0 7 3
new MethodS of enAntioSeLeCtive
SyntheSiS with SCAndiuM And SiLAnedioL
CAtALySiS
A. frAnz 1
1 University of California Davis, Department of Chemistry,
Davis, USA
Our goal is to develop catalysts and synthetic methodology
that mini-mize the use of reagents and or-ganic sol-vents, increase
efficiency, and approach 100% selec-tivity. We are investigating
the activity and selectivity of various catalyst systems for
carbon-carbon bond-forming reactions and the enantioselective
synthesis of complex molecules such as oxindoles and
spirooxindoles will be presented. Catalysts discussed will include
scandium- and indium-based chiral Lewis acids, Bronsted acids,
and silanediols as a new class of hydrogen-bonding catalysts.
Of particular interest, a catalytic asymmetric [3+2] annulation
reaction of allylsilanes with bidentate electrophiles will be
presented to generate carbocycles and heterocycles. This lecture
will also discuss mechanism and molecular insights for catalyst
activity and design.
Keywords: Asymmetric catalysis; Asymmetric synthesis;
Hydrogen bonds; Heterocycles; Silicon;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc