Synthesis of new 2-aryl and 2-heteroaryl substituted thiazolo[3,2-a]benzimidazol-3(2H)-ones and investigation of their electrochemical reduction

Synthesis of new 2-aryl and 2-heteroaryl substituted thiazolo[3,2-a]benzimidazol-3(2H)-ones and investigation of their electrochemical reduction

Oral presentation

Nikolay Lumov1, Kameliya Anichina2, Stela Georgieva2, Simeon Stoyanov1, Denitsa Pantaleeva1
1Institute of Organic Chemistry with Centre of Phytochemistry - Bulgarian Academy of Sciences
2University of Chemical Technology and Metallurgy, Sofia, Bulgaria

Benzimidazole is important heterocyclic system due to the broad spectrum of biological activities exhibited by its derivatives such as antiviral, anticancer, antihelmintics, analgesics, antihistaminic, antiparasitics, anti-ulcer, antifungals, proton pump inhibitors etc. On the other side the nitro group is also a functional group of interest for pharmacy and medicine, because it is able to undergo bioreduction in organism by special enzymes – nitroreductases, and form nitro radical anions and further cytotoxic agents in hipoxide conditions. With the aim of developing some new aryl/heteroaryl thiazolo[3,2-a]benzimidazol-3(2H)-ones able to exert selective cytotoxic effect in hypoxic conditions, we have synthesized a series of derivative containing various moieties. The target compounds were obtained by multi-step conversion of o-phenylenediamine to the corresponding thioacetic acid, thiazolobenzimidazolone and 2-aryl/heteroaryl derivatives. The molecular structure and the nitro reduction ability of the newly synthesized compounds was characterized by spectral, cyclovoltametric and theoretical DFT methods. The obtained data demonstrated that thiazolo[3,2-a]benzimidazol-3(2H)-ones could form radical anionic products in aportic medium. The nitrothiophene and nitrofuran derivatives within the series passes the highest electron affinities according to the theoretical calculations.
Keywords: thiazolobenzimidazolones, nitroreduction, cyclic voltammetry