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Optimizing dirhodium(II) tetrakiscarboxylates as chiral NMR auxiliaries

Citation

Mattiza, JT and Fohrer, JGG and Duddeck, H and Gardiner, MG and Ghanem, A, Optimizing dirhodium(II) tetrakiscarboxylates as chiral NMR auxiliaries, Organic & Biomolecular Chemistry, 9, (19) pp. 6542-6550. ISSN 1477-0520 (2011) [Refereed Article]


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Copyright Statement

Copyright 2011 Royal Society of Chemistry

DOI: doi:10.1039/c1ob05665d

Abstract

Thirteen enantiopure paddlewheel-shaped dirhodium(II) tetrakiscarboxylate complexes have been checked for their efficiency in the dirhodium method (differentiation of enantiomers by NMR spectroscopy); six of them are new. Their diastereomeric dispersion effects were studied and compared via so-called key numbers KN. Adducts of each complex were tested with five different test ligands representing all relevant donor properties from strong (phosphane) to very weak (ether). Only one of them, the dirhodium complex with four axial (S)-N-2,3-naphthalenedicarboxyl-tert-leucinate groups (N23tL), showed results significantly better for all ligands than the conventional complex Rh* [Rh(II)2[(R)-(+)-MTPA]4; MTPA= methoxytrifluoromethylphenylacetate]. On the basis of 1H{1H} NOE spectroscopy and X-ray diffraction, a combination of favourable anisotropic group orientation and conformational flexibility is held responsible for the high efficiency of N23tL in enantiodifferentiation. Both complexes, Rh* and N23tL, are recommended as chiral auxiliaries for the dirhodium experiment.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Inorganic Chemistry
Research Field:Transition Metal Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Gardiner, MG (Associate Professor Michael Gardiner)
ID Code:72192
Year Published:2011
Web of Science® Times Cited:12
Deposited By:Chemistry
Deposited On:2011-08-23
Last Modified:2017-10-25
Downloads:0

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