ISMSC 2007 - Università degli Studi di Pavia

Synthesis of Functional Aromatic Oligoamides
Fred Campbell, Jeff Plante, Barbora Malkova and Andrew Wilson
School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, United Kingdom
Astbury Centre for Structural Molecular Biology, University of Leeds, Woodhouse Lane, Leeds
LS2 9JT, United kingdom
The design and synthesis of oligomers that adopt well defined conformations [1-3] is a key goal in
developing functional supramolecular architectures that mimic those found in nature. Currently,
methods to synthesise abiotic oligomers with different sequences of monomers are lacking.
In this presentation we will discuss our initial studies on the synthesis of O and N-alkylated
O
NH2 O
R3
O
NH
NH
O R2
O-alkylated
trimers
O R1
O
HN
O
N
R 3
N
N-alkylated
macrocycles
CO2H CO2H Figure 1. Trimeric N and O alkylated aromatic oligoamide scaffolds
R 2
N-alkylated
trimers
aromatic oligoamides
derived from paminobenzoic
acid (Figure
1). We will highlight the
subtle role that the
conformation of secondary
and tertiary amides can
play in adopting helical or
extended conformations
and the role of hydrogenbonding
in promoting
extended structures. We
will also discuss how short
foldamers can be used to
access macrocycles with a
regiospecific arrangement
of functional groups.
Finally the potential for these architectures to act as inhibitors of protein-protein interactions [3]
will be discussed.
[1]S.H.Gellman,Acc. Chem. Res. 1998, 31, 178-180.
[2] I. Huc, Eur. J. Org. Chem. 2004, 17-29.
[3] Z.-T. Li, J.-L. Hou, and H.-P. Yi, Chem. Asian. J., 2006, 1, 766-778.
[3]H.YinandA.D.Hamilton,Angew. Chem.Int. Ed. 2005, 44, 4130-4163.
R 1
R 3
O
N
N
O
R 1
N
O
R 2
PSB 83
Hexafunctionalized Borromeates
Claire R Yates, Diego Benítez and J Fraser Stoddart
California NanoSystems Institute and Department of Chemistry and Biochemistry,
University of California Los Angeles, 405 Hilgard Avenue, Los Angeles, CA 90095, USA
(cryates@chem.ucla.edu)
The molecular construction of the Borromean Ring (BR) topology has been achieved[1]
successfully from 18 individual components under dynamic control that characterizes not only
the noncovalent, but also the coordinative and covalent bonds formed in the molecules.
Stabilized by a combination of 12 - stacking interactions and 30 dative bonds, six tridentate
and six bidentate ligands are spatially organized around six Zn(II) ions, such that they react
preferentially to form molecular BRs in ‘one reaction’ via the formation of 12 imine bonds.
This molecular BR topology provides a unique symmetrical, nanoscale three-dimensional
scaffold onto which unique features can be embedded at will. The significance of this research
is to introduce a further level of sophistication structure-wise into the metal containing BRs via
the construction (Box) of hexasubstituted borromeates.[2] Two orthogonal approaches have
been investigated, namely Pre-Assembly Modification – which involves the incorporation of the
desired functionality on the incipient tridentate ligand, followed by subsequent assembly of the
rings via metal template-directed synthesis, and Post-Assembly Modification – which first of all
involves the synthesis of Borromeates with pendant reactive groups attached to the incipient
tridentate ligand prior to assembly, then modification of the periphery via the introduction of a
new functional group. Herein, we show the efficient convergent formation of both hexaolefinic
and hexa-p-tolylpentenyloxy Borromeates. For comparison, in post-assembly terms, efforts
were made to incorporate six styrenic substrates to a pre-assembled olefin-modified
Borromeate core employing olefin cross metathesis (OXM).[3] The results conclude that the
making of hexasubstituted Borromeates divergently, is still an open challenge, as demonstrated
by the application of ruthenium-catalyzed OXM to a pre-assembled hexaolefinic Borromeate
core.
Cross
Metathesis
BOX
Self
Assembly
[1] a) K. S. Chichak, S. J. Cantrill, A. R. Pease, S. -H. Chiu, G. W. V. Cave, J. L. Atwood, J. F.
Stoddart, Science, 2004, 304, 1308–1312; b) S. J. Cantrill, K. S. Chichak, A. J. Peters, J. F.
Stoddart, Acc. Chem. Res., 2005, 38, 1–9.
[2] C. R. Yates, D. Benítez, S. I. Khan, J. F. Stoddart, Submitted.
[3] a) R. H. Grubbs, Tetrahedron, 2004, 60, 7117–7140; b) A. K. Chatterjee, T. -L. Choi, D. P.
Sanders, R. H. Grubbs, J. Am. Chem. Soc., 2003, 125, 1136011370.
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PSB 84