4-Azido-L-phenylalanine

4-Azido-L-phenylalanine is an unnatural amino acid, which is used as an effective vibrational reporter of local protein environments. 4-Azido-L-phenylalanine contains an Azide group and can undergo copper-catalyzed azide-alkyne cycloaddition reaction (CuAAc) with molecules containing Alkyne groups. Strain-promoted alkyne-azide cycloaddition (SPAAC) can also occur with molecules containing DBCO or BCN groups.