Synthesis of polymacrocyclic compounds via Pd-catalyzed amination and evaluation of their derivatives as metal detectors

A mini-review is dedicated to the application of Pd(0)-catalyzed amination reactions for the synthesis of polymacrocyclic compounds of various architectures. Such molecules comprise diazacrown ether moieties or structural fragments of tri- and tetraazamacrocycles, polyamine or polyoxadiamine chains of different length and aromatic spacers. Polymacrocyclic compounds thus formed possess an increased number of coordination sites and are suitable for testing as potential receptors of metal cations. Some of these macrocyclic compounds were decorated with the exocyclic dansyl fluorophore group or were coupled with porphyrin units to form polymacrocyclic conjugates. Fluorescent spectra of these compounds were studied in the presence of various metal perchlorates and several macrocycles were found to act as chemosensors or molecular probes for such cations like Cu(II), Al(III), Cr(III).

Synthesis of N- and O-Containing Macrobicycles with Central Biphenyl Moiety via Pd(0)-Catalyzed Amination Reactions

Background: Simple, efficient and enough versatile approaches to macrobicycles and macrotricycles, which are of great interest for the coordination of metal cations, were proposed in early 1990s using nucleophilic substitution reactions. Our research group was the first to begin a wide-range synthesis of N- and Ocontaining macrocycles using Pd-catalyzed amination reactions. Objective: The goal of the present research is to develop the catalytic synthesis of nitrogen- and oxygen containing macrobicycles organized around the central biphenyl moiety. Method: The method employed is the Pd(0)-catalyzed amination reactions which led to the formation of the first macrocycle comprising 3,3'-disubstituted biphenyl followed by the modification with two bromobenzyl moieties and the second Pd(0)-catalyzed macrocyclization which afforded target macrobicycles. Results: Macrocycles with the endocyclic 3,3'-disubstituted biphenyl moiety and diazadioxa, diazatrioxa, and tetraamine linkers were synthesized in 26-44% yields using Pd(0)-catalyzed amination reactions. They were modified with two 3-bromobenzyl substituents and introduced in the second Pd(0)-catalyzed macrocyclization to give macrobicycles in 8-27% yields. The result was shown to be dependent on the structure of the reacting compounds. The reaction with diazacrown ether provided a macrotricyclic derivative. Conclusion: An approach to a variety of N- and O-containing macrobicyclic compounds comprising a central biphenyl moiety and two oxadiamine (polyamine) chains via two consecutive Pd(0)-catalyzed amination reactions was elaborated.