Frontiers in Chemistry (Aug 2023)

Reactivity of ethyl nitrosoacrylate toward pyrrole, indole and pyrrolo[3,2-c]carbazole: an experimental and theoretical study

  • Alice Benzi,
  • Susana M. M. Lopes,
  • Sandra C. C. Nunes,
  • Gianluca Giorgi,
  • Lara Bianchi,
  • Cinzia Tavani,
  • Alberto A. C. C. Pais,
  • Giovanni Petrillo,
  • Teresa M. V. D. Pinho e Melo

DOI
https://doi.org/10.3389/fchem.2023.1229669
Journal volume & issue
Vol. 11

Abstract

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Nitrosoalkenes react with 8-methyl-1,6-dihydropyrrolo[3,2-c]carbazole to give both 2- and 3-alkylated products via hetero-Diels-Alder reaction followed by the cycloadduct ring-opening. Quantum chemical calculations, at DFT level of theory, were carried out to investigate the regioselectivity of the cycloaddition of ethyl nitrosoacrylate with 1,6-dihydropyrrolo[3,2-c]carbazoles as well as with pyrrole and indole, allowing a more comprehensive analysis of the reactivity pattern of nitrosoalkenes with five-membered heterocycles. Furthermore, theoretical calculations confirmed that ethyl nitrosoacrylate reacts with these heterocycles via a LUMOheterodiene-HOMOdienophile controlled cycloaddition. The reactivity of one of the oxime-functionalized 1,6-dihydropyrrolo[3,2-c]carbazole was explored and a new hexahydropyrido[4′,3':4,5]pyrrolo[3,2-c]carbazole system was obtained in high yield via a one-pot, two-step procedure.

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