title: Highly Enantioselective Nucleophilic Dearomatization of Pyridines by Anion-Binding Catalysis.
abstract: The asymmetric dearomatization of N-heterocycles is an important synthetic method to gain bioactive and synthetically valuable chiral heterocycles. However, the catalytic enantio- and regioselective dearomatization of the simplest six-membered-ring N-heteroarenes, the pyridines, is still very challenging. The first anion-binding-catalyzed, highly enantioselective nucleophilic dearomatization of pyridines with triazole-based H-bond donor catalysts is presented. Contrary to other more common NH-based H-bond donors, this type of organocatalyst shows a prominent higher C2-regioselectivity and is able to promote high enantioinductions via formation of a close chiral anion-pair complex with a preformed N-acyl pyridinium ionic intermediate. This method offers a straightforward and useful synthetic approach to chiral N-heterocycles from abundant and readily available pyridines.
authors.affiliation: Institute for Organic Chemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg (Germany). olga.garcia-mancheno@ur.de.|Straubing Center of Science for Renewable Resources (WZS), Schulgasse 16, Straubing (Germany). olga.garcia-mancheno@ur.de.
authors.forename: Olga
authors.initials: O
authors.lastname: García Mancheño
authors.affiliation: Institute for Organic Chemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg (Germany).
authors.forename: Sören
authors.initials: S
authors.lastname: Asmus
authors.affiliation: Institute for Organic Chemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg (Germany).
authors.forename: Mercedes
authors.initials: M
authors.lastname: Zurro
authors.affiliation: Institute for Organic Chemistry, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg (Germany).
authors.forename: Theresa
authors.initials: T
authors.lastname: Fischer
mesh_terms: D000838:Anions / Q000737:chemistry; D002384:Catalysis; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism; D014230:Triazoles / Q000737:chemistry*
chemical_list: D000838:Anions; D011725:Pyridines; D014230:Triazoles
keywords: anion-binding catalysis; dearomatization; enantioselectivity; pyridine; triazoles