The one-step solution-phase parallel synthesis of two structurally diverse libraries of pharmacologically important compounds is described. The presented compounds combine three privileged structures: the 2-arylethyl amine moiety, a tetrahydro(hetero)areno[c]pyridine, and a (thio)hydantoin. These compounds are synthesized by annulation of a hydantoin or a 2-thiohydantoin ring to tri- or tetracyclic scaffolds, containing the 2-arylethyl amine moiety and a tetrahydroisoquinoline, a tetrahydro-beta-carboline, or a tetrahydrofuro[3,2-c]pyridine. The annulation leads to pharmacologically relevant structural motifs such as imidazopyrroloisoquinolines, dioxoloimidazopyrroloisoquinolines, furoimidazopyrrolopyridines, and imidazopyrrolopyridoindoles. Both libraries were obtained with quantitative yields. The 36-membered hydantoin library was obtained with purities from 57 to 100% (90% average) and the 32-membered thiohydantoin library with purities from 73 to 100% (94% average).