Synthesis of Polycyclic Indolines by Utilizing a Reduction/Cyclization Cascade Reaction

European Journal of Organic Chemistry, vol. 2021, pp. 6097–6101

Abstract

Abstract Subsequent reduction and dearomatizing cyclization reactions open up an entry into the synthesis of novel N‐fused polycyclic indolines. The dearomatizing cyclization as key step of the sequence proceeds well with Cu(OTf)2 or TfOH as catalyst. At elevated temperature reduction of nitro‐substituted precursors with iron under acidic conditions affords a broad variety of polycyclic indolines directly in a two‐step cascade reaction in good to excellent yields. Using the developed protocol, the alkaloids tryptanthrin and phaitanthrin C have been prepared.

Authors 6

1. Jingyu Zhang Aachen Institut für Organische Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Organische Chemie RWTH Aachen University Landoltweg 1 Aachen 52074 Germany

2. Meilin Qu Aachen Institut für Organische Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Organische Chemie RWTH Aachen University Landoltweg 1 Aachen 52074 Germany

3. Saskia Huda Aachen Institut für Organische Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Organische Chemie RWTH Aachen University Landoltweg 1 Aachen 52074 Germany

4. Jas S. Ward

   University of Jyväskylä

   Affiliation as printed

   University of Jyvaskyla Department of Chemistry P.O. Box 35 Jyväskylä Finland

5. Kari T. Rissanen

   University of Jyväskylä

   Affiliation as printed

   University of Jyvaskyla Department of Chemistry P.O. Box 35 Jyväskylä Finland

6. Markus Albrecht corresponding Aachen Institut für Organische Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Organische Chemie RWTH Aachen University Landoltweg 1 Aachen 52074 Germany