title: Coupling-isomerization-N,S-ketene acetal-addition sequences--a three-component approach to highly fluorescent pyrrolo[2,3-b]pyridines, [1,8]naphthyridines, and pyrido[2,3-b]azepines.
abstract: Annelated 2-amino pyridines such as pyrrolo[2,3-b]pyridines, [1,8]naphthyridines, and pyrido[2,3-b]azepines can be synthesized in moderate to good yields in a consecutive one-pot three-component process by a coupling-isomerization-enamine-addition-cyclocondensation sequence of an electron-poor (hetero)aryl halide, a terminal propargyl N-tosylamine, and an N,S-ketene acetal. After the coupling-isomerization sequence, a Diels-Alder reaction with inverse electron demand of the intermediate enimine and the N,S-ketene acetal and subsequent aromatization furnish annelated 2-amino pyridines 4 that were unambiguously characterized by numerous X-ray structure analyses. These heterocycles are highly fluorescent and partially pH sensitive, and their electronic structure was studied with spectroscopic and computational methods.
authors.affiliation: Organisch-Chemisches Institut der Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany.
authors.forename: Oana G
authors.initials: OG
authors.lastname: Schramm
authors.forename: Née
authors.initials: N
authors.lastname: Dediu
authors.forename: Thomas
authors.initials: T
authors.lastname: Oeser
authors.forename: Thomas J J
authors.initials: TJ
authors.lastname: Müller