ISMSC 2007 - Università degli Studi di Pavia

PSB 85
Templated Synthesis of Large Macrocyles by Ring-Closing Metathesis
Yeni, Markus Albrecht
Institut für Organische Chemie der RWTH Aachen, Landoltweg 1, D-52056 Aachen, Germany
yeni@oc.rwth-aachen.de
The synthesis of large macrocyclic molecules is still considered as a challenge. [1]
Recently, we developed an efficient way to synthesize such macrocycles, which contain
intraanular functional groups (figure 1).
NH 2
O
O
O
O
H 2N
Figure 1: Macrocyles with intraanular nitrogen functional groups.
The synthetic strategy we applied is shown in scheme 1. We chose an organic molecule as a
template to facilitate the cyclization by ring-closing metathesis. The reaction between the
template and the compound induced a labile covalent bond in the precursor of the macrocycle
and after the cyclization we can easily remove the template by breaking the covalent bond,
which is connecting the template to the macrocycles.
Scheme 1: Synthetic strategy to prepare funtionalized macrocycles.
[1] D. H. Camacho, E. V. Salo, Z. Guan, Org. Lett., 2004, 6, 865-868
O
R NH2 H2N R
O
(CH 2) 20
(CH 2) 20
R = H, t-Bu
O
O
Application of benzopyrroles in the construction of anion receptors
Tomasz Zieliski, a Pawe Dydio a,b and Janusz Jurczak a,b
a
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224
Warsaw, Poland
b
Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland
PSB 86
Coordination chemistry of anions is one of the most active fields of supramolecular chemistry.[1]
In this research area, construction of neutral receptors that bind anions by hydrogen bonds has
been a subject of extensive exploration. In contrast to other hydrogen bond donor groups,
pyrrole moiety does not contain a built-in hydrogen bond acceptor, thus a risk of unfavorable
intramolecular bonds is diminished. Benzopyrroles preserve this advantageous feature, and in
addition they have interesting spectroscopic properties. They are also more acidic, and as a
result, they can interact with anions more strongly. These aspects make benzopyrroles an
attractive skeleton for construction of anion receptors.[2] We would like to present our studies of
ligands containing indole, carbazole or dipyrrolonaphthalene subunits.
We used indole-7-amine as an alternative to aniline for the preparation of amide-based ligands.
The replacement of aniline with indolamine can enhance anion binding for more than five times,
due to the presence of indole NHs as additional binding sites. Versatility of indoleamines as
synthons was demonstrated by the preparation of indolyl analogues of dipyrrolomethane-based
ligands.
Advantages of benzopyrroles as rigid skeletons for construction of anions receptors are
illustrated undoubtedly by bisamides derived from 1,8-diaminocarbazole. It turned out that these
simple acyclic receptors, equipped with just three anchoring points, bind anions strongly even in
the very competitive media, and that they are much better receptors than their pyrrole
analogues.
Further enrichment of ligands with additional binding sites does not necessary increase affinity
towards anions, as for example, derivatives of dipyrrolonaphthalene bind anions only
moderately. However, due to the presence of naphthalene chromophore, the
dipyrrolonaphthalene-based receptors can act as optical sensors for anions. We observed
remarkable fluorescence enhancement upon complexation of dihydrogenphosphate.
By comprehensive structural analysis of our model ligands, we were able to resolve the
relationship between their structure and binding properties.
[1] J. L. Sessler, P. A. Gale, W. S. Cho, Anion Receptor Chemistry, The Royal Society of
Chemistry, Cambridge, 2006.
[2] M. J. Chmielewski, M. Charon, J. Jurczak, Org. Lett. 2004, 6, 3501-3504; P. Pitek, V. M.
Lynch, J. L. Sessler, J. Am. Chem. Soc. 2004, 126, 16073-16076; D. Curiel, A. Cowley, P. D.
Beer, Chem. Commun. 2005, 236-238; X. M. He, S. Z. Hu, K. Liu, Y. Guo, J. Xu, S. J. Shao,
Org. Lett. 2006, 8, 333-336.