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Das A, Ghosh I, König B. Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes. Chem Commun (Camb). 2016;52(56):8695-8doi: 10.1039/c6cc04366f.
Das, A., Ghosh, I., & König, B. (2016). Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes. Chemical communications (Cambridge, England), 52(56), 8695-8. https://doi.org/10.1039/c6cc04366f
Das, Amrita, et al. "Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes." Chemical communications (Cambridge, England) vol. 52,56 (2016): 8695-8. doi: https://doi.org/10.1039/c6cc04366f
Das A, Ghosh I, König B. Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes. Chem Commun (Camb). 2016 Jul 05;52(56):8695-8. doi: 10.1039/c6cc04366f. PMID: 27333456.
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Chem Commun (Camb). 2016 Jul 05;52(56):8695-8. doi: 10.1039/c6cc04366f.

Synthesis of pyrrolo[1,2-a]quinolines and ullazines by visible light mediated one- and twofold annulation of N-arylpyrroles with arylalkynes.

Chemical communications (Cambridge, England)

Amrita Das, Indrajit Ghosh, Burkhard König

Affiliations

  1. Institut für Organische Chemie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany. [email protected].

PMID: 27333456 DOI: 10.1039/c6cc04366f

Abstract

1-(2-Bromophenyl)-1H-pyrrole and 1-(2,6-dibromophenyl)-1H-pyrrole react in the presence of catalytic amounts of rhodamine 6G () and N,N-diisopropylethylamine (DIPEA) under blue light irradiation with aromatic alkynes and subsequently cyclize intramolecularly to form pyrrolo[1,2-a]quinoline and ullazines. The reactions proceed at room temperature, avoid transition metal catalysts, and provide the target compounds in one pot in moderate to good yields. Mechanistic investigations suggest that the photo excited is reduced by DIPEA to form the corresponding radical anion , which is again excited by 455 nm light. The excited radical anion of donates an electron to the aryl bromide giving an aryl radical that is trapped by aromatic alkynes. The intermediate vinyl radical cyclizes intramolecularly and yields the product after rearomatization.

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