Studies on the methylation of 5-nitro-benzimidazoles

Methylation of 2H, 5-nitro- (1) and 2-ethyl, 5-nitro- (2) benzimidazoles se parately with methyl iodide in acetone in the presence of potassium carbona te yielded 2H, 5/6-nitro-(3A and 3B) and 2-ethyl, 5/6-nitro- (4A and 4B) me thylbenzimidazoles respectively. Methylation of 1 and 2 in dimethylformamid e in place of acetone yielded not only 3A, 3B and 4A, 4B respectively, but in addition 1,3-dimethyl-5-nitro-benzimidazol-2-one (5) was also obtained i n each case. The structure of the synthesized compounds was determined with the help of mass and H-1 NMR spectroscopic analysis.