Transition-metal mediated asymmetric synthesis. IV. Chelation of malonate esters by a chiral lanthanide shift reagent: a general method to measure theenantiomeric excess of tricarbonyl(cyclohexadienyl)iron(1+) salts

Abstract

Chelation of dimethylmalonate derivatives of variously substituted tricarbonyl(cyclohexadienyl)-iron(1+) salts by tris(3-trifluoroacetyl-(+)-camphorato)europium(III) successfully resolved the methoxy resonances due to the two epimers of the cyclohexadiene complexes in the ¹H n.m.r. spectra of racemic samples. The method provides a general means to measure enantiomeric excess of tricarbonyliron complexes.