Visible-Light-Induced Perfluoroalkylation/Cyclization to Access Perfluoroalkylated Pyrazol-5-ones via Halogen-Bond-Based Electron Donor–Acceptor (EDA) Complexes

A halogen-bond-based electron donor-acceptor (EDA) complex-promoted perfluoroalkylative cyclization of <i>N</i>-phenylmethacrylohydrazides was developed. In this reaction, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) functions as an electron donor and interacts with perfluoroiodocarbon to form the EDA complex, which produces a perfluoroakyl radical after irradiation by blue LEDs. A series of perfluoroalkylated pyrazol-5-ones were obtained in moderate to good yields under mild conditions without the requirement of any external photocatalyst.