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.