4th EucheMs chemistry congress

Poster Session 1
s1012
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - organic chemistry
P - 0 3 0 1
hiGhLy enAntioSeLeCtive
CArBoCyCLizAtionS By CoMBinAtion of AMine
And heteroGeneouS MetAL CAtALyStS
L. deiAnA 1 , A. CordovA 1 , e. JohnSton 1 ,
S. AfewerKi 1 , o. verho 1
1 Stockholm University, Organic Chemistry, Stockholm, Sweden
The first examples of one-pot highly enantioselective
dynamic kinetic asymmetric transformations involving
α,β-unsaturated aldehydes, propargylated nucleophiles and Pd (II)
nanocatalyst. These DYKATs, which proceed by a combination
of catalytic iminium activation, enamine activation and Pd (II)
nanoparticles supported on aminopropyl-modified siliceous
mesocellular foam (MCF) catalyzed carbocyclizations, gives
access to functionalized cyclopentanes, dihydrofurans and
2,5 –dihydropyrroles with up to 98% ee. The Pd (II) nanocatalyst
was found to be remarkably stable and could be recycled several
times with no leaching of the metal into solution or any change in
activity.
Keywords: asymmetric catalysis; organocatalysis;
heterogeneous catalysis; palladium; cyclization;
4 th EucheMs chemistry congress
P - 0 3 0 2
StruCture-ProPerty reLAtionShiPS of
Low-MoLeCuLAr weiGht orGAnoGeLAtorS
BASed on BiS[n-(P-AryL)-CArBAMoyLoxy]ALKAneS
o. deMir-ordu 1 , K. ALPer 2 , h. SiMSir 2
1 Abant Izzet Baysal University, Chemistry Department, Bolu,
Turkey
2 Karabuk University, Chemistry Department, Karabuk, Turkey
The organogelation phenomenon exhibited by low-molecular
weight organic compounds is the subject of increasing attention
owing to their striking self-assembling properties, their responsive
behavior and their applicability. [1, 2] Most organogels immobilizing
various organic solvents at relatively small concentrations
(≤5% wt) consist of long nanofibers self-assembled through
non-covalent interactions. The search for the tuning of mechanical
or thermal properties of the gels, the scope of gelated solvents and
morphology of the gels is elementary in the field of gel chemistry.
It is believed that structural variations provide a basis for a better
understanding of the structure-property relationships.
With this aim, we synthesized a class of Bis[N-(p-aryl)-
-carbamoyloxy]alkanes and investigated their organogelation
properties.
These compounds have been synthesized by the reaction of
p-aryl isocyanates with diols and their structures have been
determined by 1H and 13C NMR. The sol-gel transition
temperatures (T ) were determined by the dropping-ball method
gel
and differential scanning calorimeter. The morphology of the
organogelators was investigated by scanning electron microscopy.
The compounds were designed on the basis that they have
two urethane units capable of forming hydrogen bonds, an aryl
moiety substituted by electron-donating groups which increase
the strength of p-p stacking and a hydrophobic unit that can be
involved in hydrophobic interactions. It has been observed that
the synthesized compounds favored the formation of
supramolecular gels in alcohols, esters, toluene, xylene,
dichloromethane. Infrared spectroscopy indicated that the
organogelation occurred through hydrogen bonding. Crosslinked
network was observed in the electron micrographs. Different
gelation behavior was observed in different solvents by varying
the alkyl chain length and the nature of para-substituents. In most
of the cases, para-alkoxy derivatives promote gelation at lower
gelator concentration compared to para-alkyl substituted
compounds.
references:
1. Abdallah, D. J.; Weiss, R. G. Adv. Mater. 2000, 12, No.17,
1237-1246.
2. Terech, P.; Weiss, R. G. Chem.Rev. 1997, 97, 3133-3159.
Keywords: Gels; Hydrogen bonds; Supramolecular chemistry;
Pi interactions; Self-assembly;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc