ISMSC 2007 - Università degli Studi di Pavia

Template-assembled synthetic G-quartets (TASQs)
Mehran Nikan, David Perrin, John C. Sherman*
Department of Chemistry, 6174 University Blvd., Vancouver, British Columbia
Guanine bases, present in guanosine compounds, guanine-rich strands of DNA and RNA, or
DNA-like polymers are able to self-associate and form a tetrameric structure called a G-quartet
[1]. To date it has been shown that G-quartets are templated and stabilized by cations [2].
Guanine aggregation in the absence of cations results in the formation of ribbon-like structures
[3]. We investigated the assembly of guanosine compounds by coupling them to an external
rigid template. This method proved to be helpful and organized guanosines into a G-quartet
without the need of templating cations. The cavitand places guanosines in close proximity for Hbonding
and compensates for the entropy loss in organizations of four guanines into a single
unit.
H2N N
HN
N
O
N
O
O
O
N
N N
O
O
O
H 2N
O
O H
N
NH2 N N
N
O
O
N N
N
O
O
O
O
N
H
R
O
R R
O
N
O
N N
O
R
O
O
N
N N
O
O
O
N N
N
O
O
O
N
N
N
NH
The synthesis, structural features, solution behavior and stability of this system will be reported,
and the results of the cation extraction experiments will be briefly discussed.
O
NH 2
PSB 23
[1] Davis, J. T., Angewandte Chemie-International Edition 2004, 43, (6), 668-698.
[2] Pinnavaia, T. J.; Marshall, C. L.; Mettler, C. M.; Fisk, C. I.; Miles, H. T.; Becker, E. D., Journal
of the American Chemical Society 1978, 100, (11), 3625-3627.
[3] (a) Gottarelli, G.; Masiero, S.; Mezzina, E.; Pieraccini, S.; Rabe, J. P.; Samori, P.; Spada, G.
P., Chemistry-a European Journal 2000, 6, (17), 3242-3248. (b) Sessler, J. L.; Sathiosatham,
M.; Doerr, K.; Lynch, V.; Abboud, Angewandte Chemie-International Edition 2000, 39, (7), 1300.
(c) Kotch, F. W.; Sidorov, V.; Lam, Y. F.; Kayser, K. J.; Li, H.; Kaucher, M. S.; Davis, J. T.,
Journal of the American Chemical Society 2003, 125, (49), 15140-15150.
Application of Dynamic Combinatorial Chemistry in the synthesis of
polyazamacrocycles containing furan or thiophene units
Aleksandra Obrocka, a Krzysztof Ziach, a Janusz Jurczak a,b
a) Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland
b) Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52,
01-224 Warsaw, Poland
PSB 24
One of the crucial problems in supramolecular chemistry is an effective synthesis of macrocyclic
compounds of desired size and structure. Another difficulty is designing a ligand able to bind the
specific guest molecule. Dynamic Combinatorial Chemistry (DCC), new synthetic methodology,
can solve both of these problems.[1] DCC bases on reversibility of a reaction used to create the
Dynamic Combinatorial Library (DCL). Addition of a substance that interacts noncovalently with
members of the library changes the equilibrium position in the system. The imination reaction,
as a fast reversible process, is good candidate for a model reaction for DCC.[2] [3]
Herein we present the study on the imination reaction (Scheme 1) between aromatic
dialdehydes (2,5-diformylfuran and 2,5-diformylthiophene) and a,w-diamines used as building
blocks in the presence of variety of inorganic (alkaline metal) cations as templates
DCLs of resulting Schiff bases were analysed using electrospray ionization mass spectrometry
(ESI-MS). The dynamic imine libraries were “frozen” by means of NaBH4 reduction to
corresponding polyamines. HPLC technique was successfully adopted, allowing for quantitative
template effect determination.
[1] S. J. Rowan, S. J. Cantrill, G. R. L. Cousins, J. K. M. Sanders and J. F. Stoddart, Angew.
Chem. Int. Ed., 2002, 41, 899-952
[2] O. Storm and U. Luning, Chem. Eur. J., 2002, 8, 793-798
[3] A. González-Álvarez, I. Alfonso, F. López-Ortiz, A. Aguirre, S. García-Granda and V. Gotor,
Eur. J. Org. Chem. 2004, 1117