Issue 46, 2017

Improved synthesis of symmetrically & asymmetrically N-substituted pyridinophane derivatives

Abstract

The N,N′-di(toluenesulfonyl)-2,11-diaza[3,3](2,6)pyridinophane (TsN4) precursor was sought after as a starting point for the preparation of various symmetric and asymmetric pyridinophane-derived ligands. Various procedures to synthesize TsN4 had been published, but the crucial problem had been the purification of TsN4 from the larger 18- and 24-membered azamacrocycles. Most commonly, column chromatography or other laborious methods have been utilized for this separation, yet we have found an alternate selective dissolution method upon protonation which allows for multi-gram scale output of TsN4·HCl. This optimized synthesis of TsN4 also led to the development of symmetric RN4 derivatives as well as the asymmetric derivative N-(tosyl)-2,11-diaza[3,3](2,6)pyridinophane (TsHN4). Using this TsHN4 precursor, different N-substituents can be added to create a library of asymmetric RR′N4 macrocyclic ligands. These asymmetric RR′N4 derivatives expand the utility of the RN4 framework in coordination chemistry and the ability to study the electronic, steric, and denticity effects of these pyridinophane ligands on the metal center.

Graphical abstract: Improved synthesis of symmetrically & asymmetrically N-substituted pyridinophane derivatives

Supplementary files

Article information

Article type
Paper
Submitted
10 Oct 2017
Accepted
14 Nov 2017
First published
14 Nov 2017

Org. Biomol. Chem., 2017,15, 9923-9931

Improved synthesis of symmetrically & asymmetrically N-substituted pyridinophane derivatives

A. J. Wessel, J. W. Schultz, F. Tang, H. Duan and L. M. Mirica, Org. Biomol. Chem., 2017, 15, 9923 DOI: 10.1039/C7OB02508D

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