Azide click chemistry is a very popular chemistry that is widely used in pharmaceutical and biotech field due to its mild condition, fast speed and biocompatibility.
The 1st generation of azide click chemistry is enabled through the reaction of Azide (N3) with alkyne (such as propargyl group) in the presence of copper catalyst to form a stable triazole linkage.
The 2nd generation of Azide click chemistry eliminated the need to use copper through the reaction of Azide molecule with structure constrained alkynes such as DBCO (Dibenzocyclooctyne), or BCN (bicyclo[6.1.0]nonyne) bearing molecules.
The attraction of the azide functionality is its high selectivity and its stability under most conditions. These properties are especially useful where other conjugating functionalities have to be used due to their limited stability or when careful control of variables, such as pH, are needed to ensure high yielding reactions.