Synthesis of 1,3-Dioxepine-Fused (Tricyclic) Bispyrazoles Involved with Pyrazolone Derivatives and Dichloromethane.

A simple and novel method for the synthesis of novel 1,3-dioxepine-fused (tricyclic) bispyrazoles is described. It involves a Cs 2 CO 3 -mediated O -alkylation of readily available pyrazolone derivatives with dichloromethane as the methylene source followed by PhI(OAc) 2 -mediated intramolecular oxidative biheteroaryl coupling under mild conditions. This scalable protocol was applied for the preparation of valuable and novel 1,3-dioxepine-fused (tricyclic) bispyrazoles that could find applications in medicinal or material chemistry.