Synthesis of novel 2,2- and 1,1-linked dimeric ‘head-to-head’ N-alkoxybenzimidazoles

Synthesis of two new types of ‘head-to-head’ N,N-alkoxy bisbenzimidazoles is described. The proposed intermediate N-oxy benzimidazole from base-induced heterocyclization of N-alkylnitroanilines can be trapped with a biselectrophile (to give an N,N-linked dimer), or double heterocyclization of dimeric nitroanilines can be intercepted by electrophile trapping of both N-oxybenzimidazole termini to give C2,C2-linked dimers. These represent two regioisomeric motifs constituting new classes of benzimidazole dimers.