Synthetic Procedures to Access 2-Guanidinobenzazoles of Biological Interest

Benzazoles (Bz) and derivatives are interesting molecules in medicinal chemistry. Several of these compounds display diverse biological activities; some are still used in clinical applications. In this way, synthetic chemists are interested in developing new procedures to access compounds with the guanidine moiety as 2-aminobenzimidazole (2ABI), Astemizole (antihistaminic), Albendazole (anthelmintic) and Carbendazim (fungicide). The guanidine group, considered a super base bonded to a benzoxazole ring, results in the 2-guanidinobenzazoles (2GBZs), which could modify the biological activity of these heterocycles. On these bases, we prepared this review article, which covers chemical aspects of 2-guanidinobenzoazoles as potential therapeutic agents and summarizes the current knowledge on the mechanism of pharmacological activities such as cytotoxic, inhibition of cell proliferation via angiogenesis and apoptosis. Specifically, it highlights the most recent results of synthetic approaches to 2GBZs with variety of modifications and functionalization with aromatic, carbohydrate, and amino-acid moieties as illustrated on 28 schemes and is concluded with 141 references. Additionally, the format of this interesting review is exclusively designed on specifically classified category of chemical reactions with primary precursors such as o-substituted anilines and 2-aminobenzazoles (2ABZs). This will constitute the important goals and novelty of this paper to facilitate synthetic chemists in the investigation about development of new pharmacophores.