The first application of an imidazole o-quinodimethane in Diels–Alder reactions leading to the synthesis of benzimidazoles

An efficient procedure for the generation of the imidazole-4,5-quinodimethane intermediate 4 from 2-bromo-4,5-bis(bromomethyl)imidazole derivative 3 in boiling toluene in the presence of 18-crown-6 is described. o-Quinodimethane 4 was captured for the first time by several symmetrically and unsymmetrically substituted dienophiles to afford the corresponding Diels–Alder benzimidazole adducts.