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Die aus o‐Phenylendiamin (I) und Furfural oder Thiophenaldehyd (II) nach anschließender N‐Methylierung gebildeten 2‐Hetarylbenzimidazole (IV) reagieren mit Acetylnitrat, Brom, Schwefelsäure oder Paraformaldehyd/ Salzsäure zu den 5‐substituierten Verbindungen (V).

There is very little information in the literature on 4(5)-furyl-substituted imidazoles, which is caused, in our opinion, by the difficult availability of furacyl bromide and the negative result of condensing it with formamide. We have developed a preparative method of obtaining furacyl bromide 2 selectively as a result of the reaction of 2-acetylfuran (1) with copper(II) bromide. This enabled the synthesis of 4(5)-(2-furyl)imidazole 4 by the Weidenhagen [1] method by the following scheme. O O Me O O Br O O OAc O N N H CuBr 2 EtOAc / CHCl 3 AcOK MeOH 1 2 3 4 (AcO) 2 Cu · H 2 O, CH 2 O NH 4 OH, 25%On methylating compound 4 with methyl iodide in , in difference to the previously studied alkylation of 2-(2-furyl)imidazole [3], the formation of isomers is possible as a result of the asymmetry of the imidazole anion.

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