Fiche publication
Date publication
mars 2023
Journal
ACS catalysis
Auteurs
Membres identifiés du Cancéropôle Est :
Dr BELLEMIN-LAPONNAZ Stéphane
Tous les auteurs :
Vila J, Solà M, Achard T, Bellemin-Laponnaz S, Pla-Quintana A, Roglans A
Lien Pubmed
Résumé
The [2 + 2 + 2] cycloaddition of 1,5-bisallenes and alkynes under the catalysis of Rh(I) with hemilabile thioether-functionalized N-heterocyclic carbene ligands is described. This protocol effectively provides an entry to different -5,6-fused bicyclic systems with two exocyclic double bonds in the cyclohexene ring. The process is totally chemoselective with the two internal double bonds of the 1,5-bisallenes being involved in the cycloaddition. The complete mechanism of this transformation as well as the preference for the -fusion over the -fusion has been rationalized by density functional theory calculations. The reaction follows a typical [2 + 2 + 2] cycloaddition mechanism. The oxidative addition takes place between the alkyne and one of the allenes and it is when the second allene is inserted into the rhodacyclopentene that the -fusion is generated. Remarkably, the hemilabile character of the sulfur atom in the N-heterocyclic carbene ligand modulates the electron density in key intermediates, facilitating the overall transformation.
Référence
ACS Catal. 2023 03 3;13(5):3201-3210
