title: Azide: a unique dipole for metal-free bioorthogonal ligations.
abstract: Covalently bound azide on a (small) organic molecule or a (large) biomolecular structure has proven an important handle for bioconjugation. Azides are readily introduced, small, and stable, yet undergo smooth ligation with a range of reactive probes under mild conditions. In particular, the potential of azides to undergo metal-free reactions with strained unsaturated systems has inspired the development of an increasing number of reactive probes, which are comprehensively summarized here. For each individual probe, the synthetic preparation is described, together with reaction kinetics and the full range of applications, from materials science to glycoprofiling. Finally, a qualitative and quantitative comparison of azido-reactive probes is provided.
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
authors.forename: Marjoke F
authors.initials: MF
authors.lastname: Debets
authors.forename: Christianus W J
authors.initials: CW
authors.lastname: van der Doelen
authors.forename: Floris P J T
authors.initials: FP
authors.lastname: Rutjes
authors.forename: Floris L
authors.initials: FL
authors.lastname: van Delft
mesh_terms: D001386:Azides / Q000737:chemistry*; D001555:Benzene Derivatives / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D008670:Metals / Q000737:chemistry
chemical_list: D001386:Azides; D001555:Benzene Derivatives; D008670:Metals; C524146:benzyne