One-pot synthesis of 2-C-glycosylated benzimidazoles from the corresponding methanal dimethyl acetals

A series of 2-glycosyl-benzimidazoles with α-d-arabinopyranosyl, β-d-galactopyranosyl, β-d-glucopyranosyl, β-d-mannopyranosyl, and β-l-rhamnopyranosyl configurations were obtained in 52–73% yields from the corresponding C-glycosylmethanal dimethyl acetals and o-phenylenediamine under catalysis with hydrogen chloride or a strongly acidic cation-exchange resin. Intermediate benzimidazolines were spontaneously oxidized by air to produce the final products in the one-pot procedure. The prepared compounds did not show any inhibitory effect on the growth of 12 strains of five different species of pathogenic yeasts.