Azide compounds have displayed wide applications in biological chemistry and pharmaceutical chemistry. However, the classic methods to prepare these compounds usually involve long synthesis steps, harsh reaction conditions and low reaction yields. Recent chemical approaches for direct azidation via C-H activation have drawn more attention due to its high efficiency, high conversion rate and good selectivity. This review intends to explore advances for direct azidation via C-H functionalization in the last five years and discuss the proposed mechanisms. These results are applicable to the development of synthetic methodology, natural product synthesis, and protein research.

Contents
1 Introduction
2 Azidation via metal C-H activation
2.1 Guide group-based catalysts
2.2 Free radical reaction
3 Conclusion"