The classical Kagan's amides are still practical NMR chiral shift reagents:: determination of enantiomeric purity of P-chirogenic phospholene oxides

Application of the (S)-(+)-N-(3,5-dinitrobenzoyl)-1-phenylethylamine 1 and (S)-(+)-N-(3,5-dinitrobenzoyl)-1-(1-naphthyl)ethylamine 2 as chiral NMR shift agents for a variety of phospholene derivatives is described. H-1 and P-31 NMR spectra recorded in the presence of Kagan's amides 1 or 2 show well resolved signals of vinylic protons as well as P-31 signals and allow effective measurement of the enantiomeric excesses. The experimental rule for determination of the absolute configuration at P is also proposed. (C) 2003 Elsevier Science Ltd. All rights reserved.