Generation of pyrrolo[2,1‐a]isoquinoline derivatives from N‐ylides: Synthetic control and structural characterization

New pyrrolo[2,1‐a]isoquinolines were obtained by two one‐pot procedures via 1,3‐dipolar cycloaddition between the isoquinolinium N‐ylides and symmetrical acetylenic dipolarophiles, avoiding the formation of dihydro intermediates. For structural comparison, the dihydro derivatives obtained by a classical two‐stage reaction were characterized by NMR and X‐ray crystallography, allowing complete stereochemistry assignments. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:723–729, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/.20740