Pyrrole-centered pentaheterocyclic ensembles, tetrasubstituted 1-pyrroles bearing fundamental heterocycles (pyrrole, furan, thiophene, pyridine) as substituents in various combinations, were synthesized in up to 60% yield by the interaction of hetarylnitriles with ethynylhetarenes in the KOBu/DMSO system (room temperature, 1 h). The synthesis is a cascade self-organization of three molecules of ethynylhetarene and one molecule of hetarylnitrile, triggered and driven by acetylenic carbanions.
E.Yu. Schmidt (Wed,) studied this question.