Unprecedented Strong Lewis Bases-Synthesis and Methyl Cation Affinities of Dimethylamino-Substituted Terpyridines

A versatile method for the synthesis of functionalized 2,2′:6′,2′′‐terpyridines by assembly of the terminal pyridine rings is presented. The cyclization precursors—bis‐β‐ketoenamides—are prepared from 4‐substituted 2,6‐pyridinedicarboxylic acids and acetylacetone or its corresponding enamino ketone....

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2014-07, Vol.53 (29), p.7647-7651
Main Authors: Hommes, Paul, Fischer, Christina, Lindner, Christoph, Zipse, Hendrik, Reissig, Hans-Ulrich
Format: Article
Language:English
Subjects:
Acetylacetone
Affinity
Basicity
Beta
Cations
cross-coupling
DMAP analogues
ketoenamides
Lewis base
Lewis bases
Mathematical analysis
Synthesis
Terminals
terpyridines
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Summary:A versatile method for the synthesis of functionalized 2,2′:6′,2′′‐terpyridines by assembly of the terminal pyridine rings is presented. The cyclization precursors—bis‐β‐ketoenamides—are prepared from 4‐substituted 2,6‐pyridinedicarboxylic acids and acetylacetone or its corresponding enamino ketone. Treatment with trimethylsilyl trifluoromethanesulfonate induces a twofold intramolecular condensation providing an efficient access to 4,4′′‐di‐ and 4,4′,4′′‐trifunctionalized 6,6′′‐dimethyl‐2,2′:6′,2′′‐terpyridines. Using this method, hitherto unknown 4,4′′‐bis(dimethylamino)‐ and 4,4′,4′′‐tris(dimethylamino)terpyridines have been prepared that show remarkably high calculated Lewis basicities. Super Lewis bases! The hitherto unknown 4,4′′‐bis(dimethylamino)‐ and 4,4′,4′′‐tris(dimethylamino)terpyridines have been prepared by a simple and flexible synthesis. Nonafloxy‐substituted terpyridine intermediates allow smooth introduction of dimethylamino groups or palladium‐catalyzed coupling reactions. The calculated methyl cation affinities of the novel terpyridines promise unprecedented high Lewis basicities and excellent ligand properties.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201403403