Premium
Large yet Flexible N‐Heterocyclic Carbene Ligands for Palladium Catalysis
Author(s) -
Meiries Sebastien,
Le Duc Gaëtan,
Chartoire Anthony,
Collado Alba,
Speck Klaus,
Arachchige Kasun S. Athukorala,
Slawin Alexandra M. Z.,
Nolan Steven P.
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201302471
Subject(s) - carbene , imes , palladium , chemistry , catalysis , steric effects , medicinal chemistry , nickel , nitro , combinatorial chemistry , ligand (biochemistry) , stereochemistry , organic chemistry , alkyl , biochemistry , receptor
A straightforward and scalable eight‐step synthesis of new N‐heterocyclic carbenes (NHCs) has been developed from inexpensive and readily available 2‐nitro‐ m ‐xylene. This process allows for the preparation of a novel class of NHCs coined ITent (“Tent” for “tentacular”) of which the well‐known IMes ( N , N ′‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene), IPr ( N , N ′‐bis(2,6‐di(2‐propyl)phenyl)imidazol‐2‐ylidene) and IPent ( N , N ′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene) NHCs are the simplest and already known congeners. The synthetic route was successfully used for the preparation of three members of the ITent family: IPent ( N , N ′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene), IHept ( N , N ′‐bis(2,6‐di(4‐heptyl)phenyl)imidazol‐2‐ylidene) and INon ( N , N ′‐bis(2,6‐di(5‐nonyl)phenyl)imidazol‐2‐ylidene). The electronic and steric properties of each NHC were studied through the preparation of both nickel and palladium complexes. Finally the effect of these new ITent ligands in Pd‐catalyzed Suzuki–Miyaura and Buchwald–Hartwig cross‐couplings was investigated.