4th EucheMs chemistry congress

Poster Session 1
s1085
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - organic chemistry
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in Situ GenerAted dioxirAne
orGAnoCAtALyStS in
enAntioSeLeCtiveePoxidAtion reACtionS
S. M. M. SChuLer 1 , P. r. SChreiner 1
1 Institute of Organic Chemistry, Justus-Liebig University,
Giessen, Germany
Organocatalysis has become a viable strategy for the
preparation of epoxides. [1] Using carbonyl groups and Oxone
generating the corresponding dioxiranes in situ provides an
effective organocatalytic access. [2] We could identify a new
catalytic moiety (4-(trifluoroacetyl)benzoic acid) based on this
concept. In our efforts to develop multicatalysis approaches, [1c,3]
a peptide-like catalyst was synthesized to optimize the reaction
conditions for the epoxidation of 1-phenyl-1-cyclohexene
(20 mol% catalyst, 20 mol% TBABr, Oxone (3 equiv), NaHCO3 (4.6 equiv.), DCM/H O (1:1), 5 h, r.t., 95% conversion). In an
2
attempt to improve enantioselectivity, both functionalized peptide
catalysts containing a non-natural adamantane amino acid and
C -symmetric difunctionalized diamine catalysts have been
2
synthesized.
references:
1. a) K. M. Weiß, S. B. Tsogoeva, Chem. Rec. 2011, 11, 18;
b) C. E. Jakobsche, G. Peris, S. J. Miller, Angew. Chem.
Int. Ed. 2008, 47, 6707;
c) R. Hrdina, C. E. Müller, R. C. Wende, L. Wanka,
P. R. Schreiner, Chem. Commun. 2012, 48, 2498.
2. a) O. A. Wong, Y. Shi, in Asymmetric Organocatalysis,
Vol. 291 (Ed.: B. List), 2010, pp. 201;
b) D. K. Romney, S. J. Miller, Org. Lett. 2012, 14, 1138.
3. a) C. E. Müller, R. Hrdina, R. C. Wende,
P. R. Schreiner, Chem. Eur. J. 2011, 17, 6309;
b) R. C. Wende, P. R. Schreiner, Green Chem. 2012,
in press.
Keywords: Epoxidation; Organocatalysis; Peptides;
Enantioselectivity;
4 th EucheMs chemistry congress
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SyntheSiS of interLoCKed MoLeCuLeS
ContAininG ShAPe-PerSiStent MACroCyCLeS:
A CovALent teMPLAte APProACh towArdS
rotAxAneS
C. SChweez 1 , S. S. JeSter 1 , S. hÖGer 1
1 Kekulé Institute, AK Höger, Bonn, Germany
Interlocked molecules like rotaxanes or catenanes have been
attracting chemists’ interests since their discovery due to their
extraordinary shape, the synthetical challenge, and promising
chemical-physical properties, particularly in the context of
artificial devices like molecular machines. A lot of template
directed syntheses using weak interactions e.g. metal coordination
or hydrogen bonding, were established, whereas routes using
covalently bonded templates were mostly rejected. Recently, a
renaissance of this pioneer approach arose and the capability of
this method was confirmed by several published applications.
Our group employed covalently bonded templates
successfully for various purposes, particularly in syntheses
towards shape-persistent macrocycles or macrocycle encapsuled
polymers. [1] Based on this earlier work, now we used covalently
bonded templates in the synthesis of a novel [2]rotaxane
containing rigid macrocycles. A centered phenylene–ethynylene
macrocycle is threaded onto a phenylene-ethynylene rod axis and
macrocyclic stopper units prevent a slippage effectively. The
synthetic approach relies on the centered macrocycle being
connected via phenolic ester bonds to the axis and subsequently
a selective bond cleavage by nucleophilic substitution at the
carbonyl group leads from the prerotaxane to the rotaxane.
The formation of the rotaxane was confirmed by
MALDI-TOF-MS, 1H NMR and GPC. Additionally, we
visualized the [2]rotaxane by scanning tunneling microscopy at
the solid/liquid interface of 1,2,4-trichlorobenzene and highly
oriented pyrolytic graphite.
references:
1. a) K. Becker, P. G. Lagoudakis, G. Gaefke, S. Höger,
J. M. Lupton, Angew. Chem. 2007, 119, 3520-3525.
b) K. Becker, G. Gaefke, J. Rolffs, S. Höger, J. M. Lupton,
Chem. Commun. 2010, 46, 4686-4688.
Keywords: Rotaxanes; Macrocycles; Template synthesis;
Conjugation;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc