A new method for the determination of the enantiomeric purity of carboxylic acids: reaction of carboxylates with tris(tetraphenylimidodiphosphinato)praseodymium and X-ray structure of a dinuclear dicarboxylato adduct

X-Ray crystal structure of (tetraphenylimidodiphosphinato)silver(I): an unexpected tetranuclear complex with two modes of coordination of silver

“…The tetraphenylimidodiphosphinate ligand (TPIP), the 'inorganic' equivalent of b-diketonate ligands, has proven to lead to interesting complexes especially in the field of lanthanide NMR shift reagents. [1][2][3][4] Thus, Pr(TPIP) 3 , owing to its high stability with respect to hydrolysis even in the presence of acids (in contrast to b-diketonates), can be used as a shift reagent for carboxylic acids and induces important simplification in their 1 H NMR spectra. Moreover, Pr(TPIP) 3 reacts instantaneously with carboxylates to lead to dinuclear complexes: in the case of acids containing a chiral centre, these complexes can be used to control the optical purity of the starting acids.…”

A Protocol for NMR Analysis of the Enantiomeric Excess of Chiral Diols Using an Achiral Diboronic Acid Template

“…Output files from energy minimization and equilibrium geometry calculations using a semiempirical (PM3) method to calculate the lowest energy conformations of the heterochiral (meso) and homochiral boronate esters (RR and SS) derived from 1-phenyl-1,3-propanediol 1c (ZIP) 1 H and 13 C NMR spectra of bis-boronate complexes formed from reaction of diols 1a−f with 1,3-phenyldiboronic acid as well as a graphical representation and discussion of the quadratic relationship seen between the enantiomeric excess of the chiral diol and diastereomeric excess (homochiral−heterochiral) of the corresponding bis-boronate complex (PDF)…”

Camphor Derivatives in Asymmetric Cycloadditions and Rearrangements

“…11 The enantiomeric purity of these compounds was also determined, after complexation of the acids with tris(tetraphenylimidodiphospinato)praseodymium, by 500 MHz NMR spectroscopy. 12 To test the influence of a methyl group on carbon 4 on the s-cis-s-trans equilibrium of the acyloxazolinium intermediates 2a and 2b and, consequently, on the diastereoselectivity of these cycloadditions, a,b-unsaturated oxazolines 37 and 38 were prepared by the same sequence of reactions from the isomeric amino alcohol 36 13 (Scheme 4). The reactivity of these two diastereomeric oxazolines was examined with cyclopentadiene (14) and enol phosphate 19 (Figure 1).…”