3 years ago

Synthesis of Pyrrolotriazoloisoquinoline Frameworks by Intramolecular Cu-Mediated or Free Radical Arylation of Triazoles

Synthesis of Pyrrolotriazoloisoquinoline Frameworks by Intramolecular Cu-Mediated or Free Radical Arylation of Triazoles
Ivan P. Mosiagin, Olesya A. Tomashenko, Liya D. Funt, Alexander F. Khlebnikov, Mikhail S. Novikov
The cyclization of (2-bromophenyl)pyrrolyl-1,2,4-triazoles via copper-mediated intramolecular direct C-arylation of 1,2,4-triazoles was first accomplished under triazole-NHC control to give unknown fused heterocyclic skeletons, pyrrolo[3,2-c][1,2,4]triazolo[5,1-a] or [3,4-a]isoquinolines. The primary products underwent a triazole ring opening under the basic arylation conditions, providing N-(1H-pyrrolo[3,2-c]isoquinolin-5-yl)cyanamides. The formation of the cyanamides from isomeric pyrrolo[3,2-c][1,2,4]triazolo[3,4-a]isoquinolines involves, besides the triazole ring opening, the unusual migration of the cyano group. Cyanamides can be easily reduced to 1H-pyrrolo[3,2-c]isoquinolin-5-amines, the first NH2-substituted derivatives of 1H-pyrrolo[3,2-c]isoquinoline. An insight into the mechanism of the triazole ring cleavage was achieved by performing a DFT study at the B3LYP/6-31G+(d,p) level. Free radical cyclization of (2-bromophenyl)pyrrolyl-1,2,4-triazoles with TTMSS/AIBN under neutral conditions allows obtaining pyrrolo[3,2-c][1,2,4]triazolo[5,1-a] and [3,4-a]isoquinolines, as well two more new heterocyclic systems, pyrrolo[3,4-c][1,2,4]triazolo[5,1-a] and [3,4-a]isoquinolines, in good yields without triazole ring cleavage. The developed cyclizations provide a concise, atom-economical route to novel fluorescent fused polyheterocycles containing pyrrole and 1,2,4-triazole moieties.

Publisher URL: http://dx.doi.org/10.1021/acs.joc.7b01341

DOI: 10.1021/acs.joc.7b01341

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.