A novel approach to indolo[3,2-c]isoquinoline and dibenzo[c,h][1,6]naphthyridine tetracyclic systems was discovered based on switchable reduction of 2-methoxy-3-(2-nitrophenyl)-1-oxo-1,2,3,4-tetrahydroisoquinoline-4-carboxylic acid prepared via Castagnoli–Cushman reaction. Reduction with ammonium formate resulted in the expected selective transformation of the nitro group (thus providing access to substituted dibenzo[c,h][1,6]naphthyridine via cyclization and dehydrogenation). However, attempted reduction with sodium sulfide initiated a previously unknown reaction cascade including double reduction, cyclization, and decarboxylation, leading to formation of indolo[3,2-c]isoquinoline polyheterocycle in one synthetic step.

Original languageEnglish
Article number2049
Number of pages10
JournalMolecules
Volume25
Issue number9
DOIs
StatePublished - May 2020

    Scopus subject areas

  • Drug Discovery
  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Physical and Theoretical Chemistry
  • Pharmaceutical Science
  • Organic Chemistry

    Research areas

  • Castagnoli–Cushman reaction, Cryptolepine, Dibenzonaphthyridine, Heteroannulation, Hydroxamic acid, Indoloisoquinoline, Nitroarene reduction, Tetrahydroisoquinolonic acid, DESIGN, BACTERIAL SIDEROPHORES, Castagnoli-Cushman reaction, CLEAVAGE, CRYPTOLEPINE, CYCLIC ANHYDRIDES, tetrahydroisoquinolonic acid, cryptolepine, nitroarene reduction, NITROSOBENZENE, AGENTS, hydroxamic acid, indoloisoquinoline, TOPOISOMERASE-I INHIBITORS, heteroannulation, dibenzonaphthyridine

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