Reaction Mechanisms of Transition-Metal-Catalyzed Azide-Alkyne Cycloaddition “Click” Reactions: A DFT Investigation

Djamila Ikhlef (1, 2) , Changlong Wang (3) , Samia Kahlal (2) , Boubekeur Maouche (1) , Didier Astruc (3) , Jean-Yves Saillard (2)

1 LPCTCI - Laboratoire de Physico Chimie Théorique et Chimie Informatique
2 ISCR - Institut des Sciences Chimiques de Rennes
3 ISM - Institut des Sciences Moléculaires

DFT calculations at the PBE0/LANL2DZ level have been performed on model compounds to investigate the reaction mechanism of two recently reported metal-catalyzed alkyne azide cycloaddition (MAAC). The first one, that involves a [Cu(tren)]+Br- catalyst, is shown not to proceed through a metal alkynyl intermediate, but, after precomplexation of the alkyne in an η2-mode, directly to the 1,4-disubstituted 1,2,3-triazole product, through a metallacyclic transition state. The other system, involving a rare-earth Ln[N(SiMe3)2]3 complex, is found to proceed through an alkynyl-azide complex which produces an η 2-coordinated heterocyclic ligand before protonation by an incoming alkyne molecule. Our results are discussed with respect to other computational data from the literature

Keywords: Catalysis; Click reactions; Ligand effect; Coordination chemistry

Domains: Chemical Sciences; Chemical Sciences; Inorganic chemistry

Djamila Ikhlef, Changlong Wang, Samia Kahlal, Boubekeur Maouche, Didier Astruc, et al.. Reaction Mechanisms of Transition-Metal-Catalyzed Azide-Alkyne Cycloaddition “Click” Reactions: A DFT Investigation. Computational and Theoretical Chemistry, 2015, 1073, pp.131-138. ⟨10.1016/j.comptc.2015.09.020⟩. ⟨hal-01208404⟩