Synthesis of Indolizines by Dimerization of N-Propargylated Pyrroles via Allene Intermediates

Kuzu B., Gul S., Tan Uygun M., Mengeş N., BALCI M.

CHEMISTRYSELECT, vol.6, no.9, pp.2366-2372, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 6 Issue: 9
  • Publication Date: 2021
  • Doi Number: 10.1002/slct.202100045
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier
  • Page Numbers: pp.2366-2372
  • Keywords: allene, indolizine, intermolecular cyclization, radical reaction, radical scavenger
  • Middle East Technical University Affiliated: No


Ten different N-propargyl pyrrole derivatives having various substituents at the C-2 position were synthesized. These derivatives were converted into indolizine derivatives by the [2+2] cycloaddition reaction of pyrrole N-allene, forming in situ, by heating in PrOH in basic medium. The structures were characterized by NMR and X-ray crystallography. The N-propargylated derivatives smoothly underwent intermolecular cyclizations to produce indolizine derivatives in good yields. We proposed a radical mechanism for the dimerization. Reaction of an allene product with butylated hydroxytoluene (BHT), a radical scavenger, did not give any dimerization product. This result supports the radical reaction.