Five-membered N-heterocycles play an important role in organic synthesis and material chemistry, as they are widespread through pharmaceutical molecules and natural products. Chemists have developed many synthetic strategies for constructing five-membered N-heterocycles from N-centered radicals, but the availability of mild and green methods for these transformations is still limited. The cyclization of visible-lightgenerated N-centered radicals with alkenes has emerged as a powerful tool to enable these chemical transformations in recent years. Through chosen representative examples, the significant developments in this promising field were outlined, including the selection of catalysts, substrate scope, mechanistic understanding (especially density functional theory calculations), and applications. The contents of this Minireview are categorized by intramolecular cyclization and intermolecular Ncentered radical addition/cyclization reactions.

A radical cyclization of olefinic 1,3-dicarbonyls and olefinic amides with nitrile C(sp 3 )À H bonds for the preparation of valuable 2,3-dihydrofurans and benzoxazines have been developed. This protocol can be conducted at metaland base-free conditions in aqueous media with moderate to good yields. Moreover, the practicality of this strategy is further highlighted by gram-scale reactions. The mechanistic investigation reveals that the transformation is initiated by insitu formed cyanomethyl radical.