Chiral recognition of ethers by NMR spectroscopy.
Enantiomers of chiral ethers and acetals are notoriously difficult to differentiate because their reactivity is low and they are poor donors to any Lewis acid or metal ion. As an exception, epoxides are somewhat better donors. This review describes the properties of ethers, explains NMR methods for their chiral recognition and describes successful examples of ether differentiation. The majority of literature reports deals with chiral lanthanide shift reagents and dirhodium tetracarboxylate complexes, which were used as enantiopure auxiliaries to create diastereomeric adducts with dispersed (1)H and (13)C NMR signals. The various methods are compared as to which is best suited for which purpose.
Duddeck
Helmut
H
Leibniz University Hannover, Institute of Organic Chemistry, Schneiderberg 1B, D-30167 Hannover, Germany. duddeck@mbox.oci.uni-hannover.de
Gómez
Edison Díaz
ED
D004987:Ethers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010100:Oxygen / Q000737:chemistry; D055672:Static Electricity; D013237:Stereoisomerism
D004987:Ethers; D010100:Oxygen