By condensation of pyrrolidine (I) with paraformaldehyde (II) and 4-ethylpropiophenone (III) by means of dry HCl in refluxing ethyl acetate.

The condensation of 2-(dimethylamino)benzyl chloride (I) with 2-mercaptobenzimidazole (II) by means of NaHCO3 in ethanol gives 2-[2-(dimethylamino)benzylthio]benzimidazole (III), which is then oxidized with m-chloroperbenzoic acid (IV) in CHCl3-methanol.

The acylation of methylanthranilate (I) with isobutyryl chloride (II) gives 2-isobutyramidobenzoic acid methyl ester (III), which is reduced with LiAlH4 to 2-(isobutylamino)benzyl alcohol (IV). The methylation of (IV) with dimethyl sulfate yields 2-(N-isobutyl-N-methylamino)benzyl alcohol (V), which is treated with SOCl2 to afford the corresponding benzyl chloride (VI). The condensation of (VI) with benzimidazole-2-thiol (VII) by means of NaOH yields 2-[2-(N-isobutyl-N-methylamino)benzylsulfanyl)benzimidazole (VIII), which is finally oxidized with m-chloroperbenzoic acid (MCPBA) as usual.

The acylation of methylanthranilate (I) with isobutyryl chloride (II) gives 2-isobutyramidobenzoic acid methyl ester (III), which is reduced with LiAlH4 to 2-(isobutylamino)benzyl alcohol (IV). The methylation of (IV) with dimethyl sulfate yields 2-(N-isobutyl-N-methylamino)benzyl alcohol (V), which is treated with SOCl2 to afford the corresponding benzyl chloride (VI). The condensation of (VI) with benzimidazole-2-thiol (VII) by means of NaOH yields 2-[2-(N-isobutyl-N-methylamino)benzylsulfanyl)benzimidazole (VIII), which is finally oxidized with m-chloroperbenzoic acid (MCPBA) as usual.

The acylation of methylanthranilate (I) with isobutyryl chloride (II) gives 2-isobutyramidobenzoic acid methyl ester (III), which is reduced with LiAlH4 to 2-(isobutylamino)benzyl alcohol (IV). The methylation of (IV) with dimethyl sulfate yields 2-(N-isobutyl-N-methylamino)benzyl alcohol (V), which is treated with SOCl2 to afford the corresponding benzyl chloride (VI). The condensation of (VI) with benzimidazole-2-thiol (VII) by means of NaOH yields 2-[2-(N-isobutyl-N-methylamino)benzylsulfanyl)benzimidazole (VIII), which is finally oxidized with m-chloroperbenzoic acid (MCPBA) as usual.

The acylation of methylanthranilate (I) with isobutyryl chloride (II) gives 2-isobutyramidobenzoic acid methyl ester (III), which is reduced with LiAlH4 to 2-(isobutylamino)benzyl alcohol (IV). The methylation of (IV) with dimethyl sulfate yields 2-(N-isobutyl-N-methylamino)benzyl alcohol (V), which is treated with SOCl2 to afford the corresponding benzyl chloride (VI). The condensation of (VI) with benzimidazole-2-thiol (VII) by means of NaOH yields 2-[2-(N-isobutyl-N-methylamino)benzylsulfanyl)benzimidazole (VIII), which is finally oxidized with m-chloroperbenzoic acid (MCPBA) as usual.