Intramolecular Oxidative Cyclization of Hydrazones Catalyzed by Iodinated Hypercrosslinked Polymers

ABSTRACT Benzopyrano[4,3‐ c ]pyrazoline derivatives were synthesized via an intramolecular oxidative cyclization of hydrazones using an iodinated hypercrosslinked organic polymer (HCP‐I) as a reusable heterogeneous hypervalent iodine catalyst. The HCP‐I catalytic system offers mild reaction conditions, operational simplicity, and good functional group tolerance, providing an efficient access to diverse benzopyranopyrazoline derivatives. A mechanistic investigation suggested that the reaction proceeds through a radical oxidation, followed by a concerted [3+2]‐cycloaddition pathway. Biological evaluation also revealed that a synthesized benzopyrano[4,3‐ c ]pyrazoline derivative exhibited potent anti‐influenza A activity.