PTC BASED N-METHYLATION OF SOME IMIDAZOLYL NON-FUSED BIHETEROCYCLES

The syntheses of 1,1'-dimethyl 2,2'-biimidazole (1), 1-methyl 2-(2'-py ridyl) benzimidazole (2) and 1,1'-dimethyl 2,2' bibenzimidazole (3) ha ve been achieved by following a general PTC based methylation reaction of the corresponding unsubstituted analogues with dimethyl sulphate i n presence of an intermediate lipophilic phase transfer catalyst, tetr abutyl ammonium bromide (TBAB). The method has been found to be superi or to the earlier methods in terms of yield, simplicity, mild conditio ns and exclusive formation of N-methylated derivatives. The compounds have been characterised by UV, IR, H-1 & C-13 NMR and mass spectral st udies.