Copper-Catalyzed Tandem Synthesis of Indolo‑, Pyrrolo[2,1‑<i>a</i>]isoquinolines, Naphthyridines and Bisindolo/Pyrrolo[2,1‑<i>a</i>]isoquinolines via Hydroamination of <i>ortho</i>-Haloarylalkynes Followed by C‑2 Arylation

Abstract

An efficient approach for the copper-catalyzed regioselective tandem synthesis of diversely substituted indolo­[2,1-<i>a</i>]­isoquinolines <b>11a</b>–<b>r</b>, pyrrolo­[2,1-<i>a</i>]­isoquinolines <b>12a</b>–<b>d</b>, and indolo-, pyrrolo­[2,1-<i>f</i>]­[1,6]­naphthyridines <b>14a</b>–<b>f</b> via preferential addition of the heterocyclic amines onto the <i>ortho</i>-haloarylalkynes over <i>N</i>-arylation followed by intramolecular C-2 arylation is described. The scope of the developed chemistry was successfully extended for the direct synthesis of bisindolo-, pyrrolo­[2,1-<i>a</i>]­isoquinolines <b>15a</b>–<b>g</b>, a regioisomer of the bisindolo­[1,2-<i>a</i>]­quinolines used as organic single-crystal field-effect transistor. Hydroxymethyl benzotriazole, which is an inexpensive and air stable compound, has been used as a ligand to carry out this one-step conversion of simple, readily available starting materials into an interesting class of heterocyclic compounds