A facile phase-transfer catalysed N-methylation of 2-substituted benzimidazoles

N-Alkyl-2-acetylbenzimidazoles have been obtained by alkylating 2-acetylben zimidazole in CH3CN at RT for 30 min in over 90 yield using triethylbenzyla mmonium chloride as phase-transfer catalyst and anhyd. K2CO3 as base. When the same conditions are used to methylate simple 2-alkylbenzimidazoles, poo rer results were obtained. Optimum conditions have been worked out for the methylation of simple 2-alkylbenzimidazoles by changing (a) the solvent, (b ) the phase-transfer catalyst, (c) the concentration of the phase-transfer catalyst and (d) the type of phase-transfer catalysis itself. Using the opt imised conditions, a number of 1-methyl-2-alkylbenzimidazoles have been syn thesised in a facile manner.