DABCO-based ionic liquid-promoted synthesis of indeno-benzofurans derivatives: Investigation of antioxidant and antidiabetic activities

A simple and effective method for synthesis of indeno-benzofurans derivatives using polyphenols and ninhydrins is explored using an acidic catalyst based on DABCO (1,4-diaza bicycle [2.2.2] octane)-based ionic liquid. The products of these types of reactions have very low yields without catalysts, but with DABCO-AIL, the yields are excellent, reaction times are reduced, and the media are cleaner. Using infrared (IR), proton nuclear magnetic resonance (1H NMR), Carbon-13 nuclear magnetic resonance (13C NMR), and mass spectrometry, the structures of products can be confirmed. There is evidence that oxidative stress plays a role in the pathophysiology of numerous diseases, including diabetes. Therapeutic antioxidants are promising candidates for the prevention and treatment of such diseases. To investigate the antioxidant properties of all synthesized derivatives, the 2,2-diphenyl-1-picrylhydrazylhydrazyl-hydrate (DPPH) assay was used. Derivatives 3d and 4 with the highest antioxidant effect (with IC50 value of 0.015 µmol/mL) were selected to evaluate the anti-diabetic effect using the Bernfeld method. The best result was seen at 0.8 mg/mL of 4 derivative and results of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test revealed that 4 at this concentration lacked cellular toxicity, too.

One-pot synthesis of benzofurans via heteroannulation of benzoquinones

Three different reactions were explored leading to the synthesis of various benzofurans. All reactions took place under AcOH catalysis in a one-pot manner. As a result, benzoquinone derivatives underwent heteroannulation with either itself or cyclohexanones to produce furanylidene-benzofuran or benzofuran structures, respectively.