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Rezorcarenty i ich pochodne. Część 1. Synteza i struktura

Urbaniak M., Iwanek W.

Wiadomości Chemiczne

2004

[Z] 58, 3-4

203-243

One of the main goals of supramolecular chemistry is to use bowl-shaped molecules to recognize a substrate on the basis of size, shape, functionality and electrostatic profile. Design and investigation of molecules which are capable to form well defined, functional supramolecular structures has attracted considerable interest during the last three decades. This concept was borrowed from biological systems where the process of molecular recognition is central to the chemistry of life. Among the molecules possessing the suitable shape and properties, there is a class of polycyclic mocromolecules-the resorcarenes. They have the cavities, whose geometries depend on the molecular structure, and the walls of these cavities contain active sites, which serve for the substrate binding. Availability of many active sites makes such a molecule a suitable platform for the synthesis of many new types of resorcarenes. The synthesis of compounds of type l, derived from resorcinol and aldehydes, has already been described very carly but the structures of such a compound were confirmed by Erdtman et. al. in 1968 by crystallographic analysis. The non-planar structure of resorcarenes makes it possible for them to exist in several different conformations. Resorcarenes can be prepared in high yield in a one-step procedure with neither template nor high dilution effects. In most cases, the mineral acids are applied as the catalysts for condensation of polyhydroxyphenols (i.e. pyrogallol or resorcinol) or the derivatives thereof with aldehydes. However, preparations of these macrocycles making use of Lewis acids or bases as catalysts are known also. The effective method of controlling the spatial structure and physico-chemical properties of resorcarenes consists in: modification of the aldehyde type used, introduction of the substituent ortho to the hydroxy groups, and functionalization of the OH groups. The electrophilic substituents such as bromo or diazo group can be readily introduced at the ortho position. However, the most freduently employed electrophilic substitution in resorcarenes in the Mannich reaction. Depending on the type and amounts of the reactants, one can obtain the aminomethyl, oxazine or oxazolidine derivatives. In turn, the hydroxy groups of resorcarenes can be functionalized in several ways, by: 1. Modification of all OH groups, e.g. by formation of the ester, ether, alcohol, silicon, phosphorus and bipyridyl derivatives; 2. Selective modification of OH groups by formation of the acetyl derivatives; 3. Covalent linking of the hydroxy groups of the neighbouring phenyl rings with the bridges containing the appropriate number of atoms. The last of the above approaches leads to the synthesis of cavitands which are in turn employed in the synthesis of the double resorcarenes, named carcerands and carcaplexes. The presented paper is a continuation of work published in Wiadomości Chemiczne in 1997. Now, we present the development of methods for the synthesis of different derivatives of resorcarenes described in literature till now. The second part will concetrate on complexation properties of resorcarenes and the third part on their applications.