Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues

Diversity Oriented Strategy (DOS) for the Efficient Synthesis of Benzofuro[2,3-b]pyridine Derivatives with Anticancer Activity

Benzofuropyridines (BFP) are polycyclic compounds with known applications in neuronal diseases. However, its derivatization patterns and anticancer potential remains unexplored. Leveraging the idea of diversity-oriented synthesis (DOS), we developed a highly efficient synthetic route for BFP, to increase the library of available analogs producing three compounds in one reaction set up, including the 2O-, 6O-, and the 1 N-substituted species, also synthesizing the unusual 2-pyridone derivatives. Key bromination reaction of the BFP moiety was successfully described which can widen the available variation in the compound's structure. The cytotoxic activity of the compounds was assessed against SH-SY5Y (neuroblastoma), HepG2 (hepatocellular carcinoma), Kb (human oral epidermoid), HeLa (cervical) and MCF-7 (breast) cancer cell lines. In the series, the m-bromobenzyl (5 b), methylcyano (5 g) and propargyl (5 h) 2O-derivatives demonstrated good selectivity against cancer cells with selectivity index (SI) of >71 for 5 g against HeLa over the normal cells, as compared to the standard drug, Doxorubicin (SI=6.7). The quantitative structure-activity relationship (QSAR) analysis revealed an impressive correlation of the defined descriptors with the bioactivity having an R2 value of 0.971 and 0.893 for Kb and HeLa respectively. Altogether, our work highlighted new information on the synthesis of BFP derivatives with potent cytotoxic activity.

2-Imidazolidinone benzofurans as unexpected outcome of the Lewis acid mediated Nenitzescu reaction

Herein, a metal-free methodology towards 2-imidazolidinone benzofurans via piperazinone enaminoesters addition onto quinones and subsequent rearrangement has been disclosed.

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

A metal-free protocol for the direct bis-arylation of 2,5-dichlorobenzoquinone with aryldiazonium salts is reported. The reactive salts are generated in situ and converted to radicals through irradiation with visible light. Reaction products precipitate from the solvent, eliminating the need for purification and thus providing a novel green method for the synthesis of versatile bis-electrophiles.