Solvent Moisture-Controlled Self-Assembly of Fused Benzoimidazopyrrolopyrazines with Different Ring's Interposition.

This article shows that two extremely important families of fused heterocyclic assemblies, namely 6-methylbenzo[4,5]imidazo[1,2-]pyrrolo[2,1-]pyrazine and 5a-methyl-5a,6-dihydro-5,12-benzo[4,5]imidazo[1,2-]pyrrolo[1,2-]pyrazine, can be synthesized from only two available building blocks (-allenylpyrrole-2-carbaldehyde and -phenylenediamine) by controlling only one reaction parameter (water content of the medium). It should be emphasized that the latter class of compounds (with an arrangement) is previously unknown. If the allene group is introduced not into the starting compound, but during the reaction (in superbase media), a heterocyclic ensemble, 5-methylbenzo[4,5]imidazo[1,2-]pyrrolo[2,1-]pyrazines, with a different position of the methyl group is formed.