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Terminal Alkyne Coupling Reactions through a Ring: Mechanistic Insights and Regiochemical Switching
Author(s) -
Storey Caroline M.,
Gyton Matthew R.,
Andrew Rhiann E.,
Chaplin Adrian B.
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201807028
Subject(s) - alkyne , chemistry , coupling reaction , ligand (biochemistry) , selectivity , pincer movement , stereochemistry , rhodium , pincer ligand , coupling (piping) , reaction mechanism , ring (chemistry) , combinatorial chemistry , catalysis , organic chemistry , receptor , materials science , biochemistry , metallurgy
The mechanism and selectivity of terminal alkyne coupling reactions promoted by rhodium(I) complexes of NHC‐based CNC pincer ligands have been investigated. Synthetic and kinetic experiments support E‐ and gem‐enyne formation through a common reaction sequence involving hydrometallation and rate‐determining C−C bond reductive elimination. The latter is significantly affected by the ligand topology: Employment of a macrocyclic variant enforced exclusive head‐to‐head coupling, contrasting the high selectivity for head‐to‐tail coupling observed for the corresponding acyclic pincer ligand.