Copper-Catalyzed Aerobic Cyclization of β,γ-Unsaturated Hydrazones with Concomitant CC Bond Cleavage

Article abstract of DOI:10.1021/acs.orglett.0c02911

A Cu-catalyzed aerobic oxidative cyclization of β,γ-unsaturated hydrazones for the preparation of pyrazole derivatives has been developed. The hydrazonyl radical promoted the cyclization, along with a concomitant CC bond cleavage of β,γ-unsaturated hydrazones. This process has been verified via several control experiments, including a radical-trapping study, an 18O-labeling method, and the identification of the possible byproducts. The advantages of this reaction include operational simplicity, a broad reaction scope, and a mild selective reaction process.