A visible light photocatalytic cross-dehydrogenative coupling/dehydrogenation/6π-cyclization/oxidation cascade: synthesis of 12-nitroindoloisoquinolines from 2-aryltetrahydroisoquinolines.
A visible light-induced photocatalytic dehydrogenation/6π-cyclization/oxidation cascade converts 1-(nitromethyl)-2-aryl-1,2,3,4-tetrahydroisoquinolines into novel 12-nitro-substituted tetracyclic indolo[2,1-a]isoquinoline derivatives. Various photocatalysts promote the reaction in the presence of air and a base, the most efficient being 1-aminoanthraquinone in combination with K3 PO4 . Further, the 12-nitroindoloisoquinoline products can be accessed directly from C1-unfunctionalized 2-aryl-1,2,3,4-tetrahydroisoquinolines by extending the one-pot protocol with a foregoing photocatalytic cross-dehydrogenative coupling reaction, resulting in a quadruple cascade transformation.
Department of Chemistry, Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany).
Fabian
F
Rusch
Department of Chemistry, Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany).
Lisa-Natascha
LN
Unkel
Department of Chemistry, Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany).
Dirk
D
Alpers
Department of Chemistry, Institute of Inorganic Chemistry, University of Hamburg, 20146 Hamburg (Germany).
Frank
F
Hoffmann
Department of Chemistry, Institute of Organic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany). malte.brasholz@chemie.uni-hamburg.de.
Malte
M
Brasholz
cascade reactions; heterocycles; organocatalysis; photocatalysis