Oxone-DMSO Triggered Methylene Insertion and C(sp²)−C(sp³)‑H−C(sp²) Bond Formation to Access Functional Bis‑Heterocycles

Metal-free insertion of a methylene group was achieved for the construction of a new C­(sp2)–C­(sp3)-H–C­(sp2) bond in order to prepare novel bis-heterocyclic scaffolds. The complete mechanistic investigations included experimental study and DFT calculations, and various symmetric and unsymmetric bis-pyrazoles as well as other pyrazole-based bis-heterocyclic molecules were prepared in moderate to high yields. Further modification of the bridged methylene group in the unsymmetric pyrazoles generated a chiral center to extend the scope of this method.