2H-benzimidazoles (isobenzimidazoles). Part 10. Synthesis of polysubstituted o-phenylenediamines and their conversion into heterocycles, particularly 2-substituted benzimidazoles with known or potential anthelminthic activity

Article abstract of DOI:10.1016/0040-4020(95)00642-L

Polysubstituted o-phenylenediamines were synthesised in moderate to high yield by reductive cleavage of the corresponding 2H-benzimidazole-2-spirocyclohexane with sodium dithionite in aqueous ethanol and converted into methyl benzimidazole-2-carbamates and 2-methylthio- and 2-trifluoro-methylbenzimidazoles with known or potential anthelminthic activity. 5-(Pyrimidin-2-ylthio)-benzimidazole and 11-(pyridin-2-ylthio)dibenzo[a,c]phenazine were synthesized too. Attempts to oxidise 1,3-dihydro-2H-4,9-diazanaphth[2,3-d]imidazole, prepared by condensation of 2,3-diaminoquinoxaline with cyclohexanone, to an analogue of the title system failed.