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: Benzimidazole (BI) and derivatives are interesting because several of these compounds have been found to have a diversity of biological activities with clinical applications. In view of their importance, the synthesis of BI and its derivatives is still considered as a challenge for synthetic chemists. Examples of compounds used in medicinal chemistry containing BI, as important nucleus, are Astemizole (antihistaminic), Omeprazole (antiulcerative) and Rabendazole (fungicide), some of these compounds have the 2- aminobenzimidazole (2ABI) as base nucleus. The structure of 2ABI derivatives contains a cyclic guanidine moiety, which is interesting because of its free lone pairs, labile hydrogen atoms and planar delocalized structure. The delocalized 10-π electron system and the extension of the electron conjugation with the exocyclic amino group, in 2ABI, making these heterocycles to have amphoteric character. The 2ABI has been used as building blocks for the synthesis of several BI derivatives as medicinally important molecules. On these bases, herein, we present a bibliographic review concerning the recent methodologies used in the synthesis of 2ABIs, including the substituted ones.

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It is know that compounds with phenol and thiol moieties have antioxidant activity. Therefore, the aim of this study was to synthetized three compounds containing phenol and thiol groups ((cysteine‐phenol (1), benzothiazole‐phenol (2) and benzothiazole‐phenol (3)) to test then as antioxidant agents. The antioxidant activity evaluation was carried out by DPPH determination and by inactivation of •OH radical generated during the Fenton reaction. The results show that DPPH radical reduction is concetration dependent, the compounds (1) and (2) have higher DPPH radical reducing power (>90%) to 0.102 μM, in comparision with N‐acetylcysteine (NAC) which show 55%. The three compounds inhibit the formation of •OH radical during the Fenton reaction by reducing the signal strength between the adduct formed by •OH and N‐tert‐butyl‐á‐phenylnitrone. In conclussion these compounds have higher antioxidant activity than NAC