A Visible Light Photocatalytic Cross‐Dehydrogenative Coupling/Dehydrogenation/6π‐Cyclization/Oxidation Cascade: Synthesis of 12‐Nitroindoloisoquinolines from 2‐Aryltetrahydroisoquinolines |
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| Authors: | Fabian Rusch Lisa‐Natascha Unkel Dirk Alpers Dr Frank Hoffmann Prof?Dr Malte Brasholz |
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| Institution: | 1. Department of Chemistry, Institute of Organic Chemistry, University of Hamburg, Martin‐Luther‐King‐Platz?6, 20146 Hamburg (Germany);2. Department of Chemistry, Institute of Inorganic Chemistry, University of Hamburg, 20146 Hamburg (Germany) |
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| Abstract: | 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 indolo2,1‐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 K3PO4. 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. |
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| Keywords: | cascade reactions heterocycles organocatalysis photocatalysis |
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