Alkylation of 4-hydroxyacetanilide (I) with n-propyl bromide provided 4-propoxyacetanilide (II). Aromatic nitration of (II) with fuming nitric acid in the presence of acetic anhydride afforded the nitro acetanilide (III), which was further hydrolyzed to the nitro aniline (IV) under basic conditions. Subsequent catalytic hydrogenation of the nitro group of (IV) furnished the phenylenediamine (V). Cyanocarbamate (VI), generated from cyanamide and methyl chloroformate, was then condensed with 4-propoxy-1,2-phenylenediamine (V) in hot pyridine to provide the title benzimidazolyl carbamate.

An new process for the preparation of the precursor phenylenediamine (V) has been reported. The previously reported 5-chlorobenzimidazole-2-spirocyclohexane (VII) was treated with sodium propoxide to yield the propoxy derivative (VIII). Sodium dithionite reduction of (VIII) gave rise to the target phenylenediamine (V) via intermediate (IX). Then, condensation of diamine (V) with cyanamide and methyl chloroformate produced the target benzimidazole derivative.

Alkylation of 4-hydroxyacetanilide (I) with n-propyl bromide provided 4-propoxyacetanilide (II). Aromatic nitration of (II) with fuming nitric acid in the presence of acetic anhydride afforded the nitro acetanilide (III), which was further hydrolyzed to the nitro aniline (IV) under basic conditions. Subsequent catalytic hydrogenation of the nitro group of (IV) furnished the phenylenediamine (V). Cyanocarbamate (VI), generated from cyanamide and methyl chloroformate, was then condensed with 4-propoxy-1,2-phenylenediamine (V) in hot pyridine to provide the title benzimidazolyl carbamate.