A series of novel polycyclic structures, with an imidazothiazole central core, were successfully synthesized through the anodic oxidation of catechols in the presence of 2-imidazolidine thione, as nucleophiles in aqueous solution. The cyclic voltammetric results indicated that one-pot multi-step sequential reactions occur between the electrochemically derived o-benzoquinones intermediates and nucleophiles affording fused polyheterocyclic compounds. The mechanism of these catalyst-free, tandem reactions are proved as ECECE or ECECCE pathways using potentiostatic and galvanostatic coulometries. In addition, the electrosyntheses of fused imidazo[2,1-b]thiazoles have been successfully performed in ambient conditions in an undivided cell using an environmentally friendly method with high atom economy and current efficiency. The novel fused polyheterocycles were fully characterized by FT-IR, 1 H NMR, 13 C NMR, and HR-MS spectrometric methods.
A series of novel catechol‐fused tetracyclic compounds, with an imidazo[2,1‐b]thiazole central core, were successfully synthesized through the anodic oxidation of catechols in the presence of 2‐mercaptobenzimidazole in aqueous solution. The cyclic voltammetric results indicate that a one‐pot four‐step sequential reaction occurs between 2‐mercaptobenzimidazole and the electrochemically derived o‐benzoquinones affording fused polyheterocyclic compounds. The mechanism of this catalyst‐free, domino reaction is proved as an ECEC pathway using controlled‐potential coulometry. In addition, the electrosyntheses of fused compounds have been successfully performed in ambient conditions in an undivided cell using an environmentally friendly method with high atom economy. The structures of products were characterized by FT‐IR, 1H NMR, 13C NMR, and HRMS spectrometric methods.
For the first time the title compounds (III) are synthesized through anodic oxidation from commercially available starting materials without any base, acid or metal catalyst.
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