On the Use of N,N'-Dipyrrolylmethane in Heterocyclic Synthesis. Dipyrrol-2H-imidazole and its Aromatic Anion

Article abstract of DOI:10.1002/hlca.19800630510

The pyrrolate ion (5) is shown to produce N, N'-dipyrrolyl methane (4) when reacted with dichloromethane under conditions of weak counter-ion association. 1-Azoniafulvene ion (13) is sggested to be the key intermediate in this reaction.N,N'-dipyrrolyl methane (4) undergoes intramolecular oxidative coupling when treated with butyllithium and Cu(II)chloride, yielding the novel ring system of dipyrrolo<1,2c:2',1'-e>-2H-imidazole (3).The latter upon reaction with methyl lithium forms the Hueckel-aromatic anion 2.Solutions of the lithium salt are stable for several days.Reaction of the dianion of 2,2'-bipyrrole (11) with dichloromethane doesi40 not produce 3, but a pyrrolophane-type dimer (12) having its two anticoplanar N,N'-bipyrrolediyl subunits arranged in a double layer and joined by a methylene group on each side.