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Pseudo‐ C 2 ‐Symmetric Bimetallic Bissalen Catalysts for Efficient and Enantioselective Ring‐Opening of meso ‐Epoxides
Author(s) -
Ma DaYou,
Xiao ZeYun,
Etxabe Julen,
Wärnmark Kenneth
Publication year - 2012
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201200018
Subject(s) - catalysis , bimetallic strip , ring (chemistry) , chemistry , enantioselective synthesis , trifluoromethanesulfonate , medicinal chemistry , cyclohexene , ligand (biochemistry) , epoxide , trimethylsilyl , solvent , stereochemistry , organic chemistry , biochemistry , receptor
Bimetallic catalysts have been synthesised based on Jacobsen’s C 2 ‐symmetric bissalen ligand. They constitute the first examples of compounds with pseuodo‐ C 2 symmetry, owing to the presence of two different metal ions. They have been investigated in the ring‐opening of meso ‐epoxides by trimethylsilyl azide (TMSN 3 ). Pseudo‐ C 2 ‐symmetric [Cr III Co]–bissalen complexes were the best in inducing ee (93–94 %) in the ring‐opened product of cyclohexene oxide by TMSN 3 under solvent‐free conditions, whereas a pseudo‐ C 2 ‐symmetric [Cr III Mn III ]‐bissalen complex displayed the highest turnover frequency (183 h −1 ) but induced a lower ee (66 %). A broad substrate scope was displayed by a pseudo‐ C 2 ‐symmetric [Cr III Co]–bissalen catalyst: at 0.1 mol % catalytic loading and under solvent‐free conditions, it induced the highest ee to date in the ring‐opened product of a range of different meso ‐epoxides by using TMSN 3 .