Ar. Katritzky et al., Novel syntheses of indolizines and pyrrolo[2,1-a]isoquinolines via benzotriazole methodology, J ORG CHEM, 64(20), 1999, pp. 7618-7621
Indolizines and pyrrolo[2,1-a]isoquinolines are synthesized by 1,3-dipolar
cycloadditions of pyridinium benzotriazolylmethylides or isoquinolinium ben
zotriazolylmethylides with ethylenes and acetylenes.