Reaction of Quinones and Guanidine Derivatives: Simple Access to Bis-2-aminobenzimidazole Moiety of Benzosceptrin and Other Benzazole Motifs

A new strategy for the synthesis
of 2-aminobenzimidazol-6-ols via
a reaction of quinones with guanidine derivatives is reported. Sequential
application of this methodology provided a simple access to the first
benzosceptrin analogue bearing a bis-2-aminoimidazole moiety. A concomitant
addition of two guanidines to the naphtho­[1′,2′:4,5]­imidazo­[1,2-a]­pyrimidine-5,6-dione, which includes the redox neutral
debenzylation and guanidine-assisted cleavage of the 2-aminopyrimidine
part resulted in the synthesis of the free challenging contiguous
bis-2-aminoimidazole moiety of benzosceprins in one step.