2H-BENZIMIDAZOLES (ISOBENZIMIDAZOLES) .10. SYNTHESIS OF POLYSUBSTITUTED O-PHENYLENEDIAMINES AND THEIR CONVERSION INTO HETEROCYCLES, PARTICULARLY 2-SUBSTITUTED BENZIMIDAZOLES WITH KNOWN OR POTENTIAL ANTHELMINTHIC ACTIVITY

摘要

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-trifluoromethylbenzimidazoles with known or potential anthelminthic activity. 5-(Pyrimidin-2-ylthio)benzimidazole and 11-(pridin-2-ylthio)dibenzo[a,c]phenazine were synthesised 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. [References: 31]