Benzimidazoles from D-glucose derivatives

Benzimidazole derivatives are compounds of great interest by their applications as pharmaceuticals, exhibiting a variety of biological applications. However, few samples of benzimidazoles linked to monosaccharides are described. Herein, we report the synthesis of benzimidazoles from D-glucose derivatives.


Introduction
Heterocycles coupled with a carbohydrate moiety show a high chemotherapeutic potential, with biological properties such as antitumor and antiviral activities, and have been studied as building blocks in syntheses of products with great medicinal value.
The most of the syntheses of benzimidazoles are carried out from aromatic aldehydes and o-phenylenediamine and its derivatives.Only a limited number of works are referred to monosaccharide derivatives as the aldehydic product.
An O-propargylated aldehyde derived from diacetone glucose was chosen for a general synthesis of triazole linked chiral benzimidazoles. 1 When 2,3-naftalendiamine is reacted with aldoses in AcOH, with iodine as oxidant, aldo-naftimidazoles were obtained in good yields and used to form fluorescent markers. 2 Iminosugars linked to benzimidazole rings have been described as glycosidase inhibitors. 3Thus, pyrrolidines linked to benzimidazole showed inhibitory activities against α-L-Fucosidases.
When a deprotected monosaccharide reacts with o-fenilendiamine in oxidative conditions, the free hydroxyl groups can be affected.In fact, when we tested the oxidative condensation of D-glucose with I 2 in AcOH or Cu(NO 3 ) 2 • 3 H 2 O, mixtures of compounds were obtained.
With the aim of obtaining good results of monosaccharide derivatives linked to benzimidazoles we planned to start with the aldehyde 1 4