title: Unprecedented strong Lewis bases--synthesis and methyl cation affinities of dimethylamino-substituted terpyridines.
abstract: 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.
authors.affiliation: Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin (Germany); Current address: Helmholtz-Zentrum Geesthacht, Institut für Biomaterialforschung, Kantstrasse 55, 14513 Teltow (Germany).
authors.forename: Paul
authors.initials: P
authors.lastname: Hommes
authors.forename: Christina
authors.initials: C
authors.lastname: Fischer
authors.forename: Christoph
authors.initials: C
authors.lastname: Lindner
authors.forename: Hendrik
authors.initials: H
authors.lastname: Zipse
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Reissig
keywords: DMAP analogues; Lewis bases; cross-coupling; ketoenamides; terpyridines