Methylene-Tethered Arylsulfonation and Benzotriazolation of Aryl/Heteroaryl C-H Bonds with DMSO as a One-Carbon Surrogate

The Selectfluor-mediated approach toward the synthesis of methylene-tethered arylsulfonation and benzotriazolation of imidazopyridines has been described. The reaction involves imidazopyridine, aryl sulfinate, or benzotriazole and dimethyl sulfoxide (DMSO) in the presence of Selectfluor, where DMSO acts as a one-carbon synthon. The protocol has been extended to the methylene-tethered arylsulfonation and benzotriazolation of β-naphthols. The mechanistic insights show that the intermediate 3-((methylthio)methyl)-2-phenylimidazo[1,2-a]pyridine is generated from imidazopyridine, DMSO, and Selectfluor. The nucleophilic displacement by the aryl sulfinate salt or benzotriazole on the intermediate afforded the product.

3-Aryl-substituted imidazo[1,2-a]pyridines as antituberculosis agents

Novel inhibitors are needed to tackle tuberculosis. Herein, we report the 3-aryl-substituted imidazo[1,2-a]pyridines as potent antituberculosis agents. A small library of 3-aryl-substituted imidazo[1,2-a]pyridines was synthesized using direct arylation, followed by nitro reduction and finally Pd-catalyzed C-N coupling reactions. The compounds thus obtained were evaluated against Mycobacterium tuberculosis H37Rv. Compound 26 was identified as an antituberculosis lead with a minimum inhibitory concentration of 2.3 μg/ml against M. tuberculosis H37Rv. This compound showed a selectivity index of 35. The docking of 26 in the active site of the M. tuberculosis cytochrome bc1 complex cytochrome b subunit (Mtb QcrB) revealed key π-π interactions of compound 26 with the Tyr389 and Trp312 residues of Mtb QcrB.