Radical reactions were applied widely in organic synthesis about three decades ago, but most of the synthetic applications have concerned on carbon-centered radicals, while heteroatom-centered radicals have received much less scrutiny. The cyclizations of nitrogen radicals in organic synthesis have gained increasing attentions in the past few years, because it is very important for synthesizing N-heterocycle compounds, such as lactams, pyrrolidines, alkaloids and so on. This review describes the recent progress of nitrogen radicals on the cyclization to form various N-heterocycles.

Key words: radical reaction, organic synthesis, nitrogen radical, cyclization, N-heterocycle