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Enantioselective Alkynylation of 2‐Trifluoroacetyl Imidazoles Catalyzed by Bis‐Cyclometalated Rhodium(III) Complexes Containing Pinene‐Derived Ligands
Author(s) -
Zheng Yu,
Harms Klaus,
Zhang Lilu,
Meggers Eric
Publication year - 2016
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.201602372
Subject(s) - enantioselective synthesis , rhodium , chemistry , benzoxazole , catalysis , alkynylation , chirality (physics) , desymmetrization , planar chirality , iridium , asymmetric induction , ligand (biochemistry) , benzothiazole , combinatorial chemistry , organic chemistry , stereochemistry , biochemistry , chiral symmetry breaking , physics , receptor , quantum mechanics , nambu–jona lasinio model , quark
Chiral rhodium(III) complexes containing two cyclometalating 2‐phenyl‐5,6‐( S , S )‐pinenopyridine ligands and two additional acetonitriles are introduced as excellent catalysts for the highly enantioselective alkynylation of 2‐trifluoroacetyl imidazoles. Whereas the ligand‐based chirality permits the straightforward synthesis of the complexes in a diastereomerically and enantiomerically pure fashion, the metal‐centered chirality is responsible for the asymmetric induction over the course of the catalysis. For comparison, the analogous iridium congeners provide only low enantioselectivity, and previously reported benzoxazole‐ and benzothiazole‐based catalysts do not show any catalytic activity for this reaction under standard reaction conditions.