NMR Quantification of Hydrogen-Bond-Accepting Ability for Organic Molecules.

The hydrogen-bond-accepting abilities for more than 100 organic molecules are quantified using F and P NMR spectroscopy with pentafluorobenzoic acid (PFBA) and phenylphosphinic acid (PPA) as commercially available, inexpensive probes. Analysis of pyridines and anilines with a variety of electronic modifications demonstrates that changes in NMR shifts can predict the secondary effects that contribute to H-bond-accepting ability, establishing the ability of PFBA and PPA binding to predict electronic trends. The H-bond-accepting abilities of various metal-chelating ligands and organocatalysts are also quantified.

NMR quantification of H-bond donating ability for bioactive functional groups and isosteres.

The H-bond donating ability for 127 compounds including drug fragments and isosteres have been quantified using a simple and rapid method with P NMR spectroscopy. Functional groups important to medicinal chemistry were evaluated including carboxylic acids, alcohols, phenols, thioic acids and nitrogen group H-bond donors. P NMR shifts for binding to a phosphine oxide probe have a higher correlation with equilibrium constants for H-bonding (log K) than acidity (pK), indicating that these binding experiments are representative of H-bonding ability and not proton transfer.

NMR Quantification of the Effects of Ligands and Counterions on Lewis Acid Catalysis.

The relative Lewis acidity of a variety of metal-ligand catalyst complexes is quantified using P NMR spectroscopy. Three P NMR probes, including two new bidentate binding probes, are compared on the basis of different binding modes (i.e.

Lanthanum(III)-Catalyzed Three-Component Reaction of Coumarin-3-carboxylates for the Synthesis of Indolylmalonamides and Analysis of Their Photophysical Properties.

New methodology has been developed for the Lewis acid catalyzed synthesis of malonamides. First, the scandium(III)-catalyzed addition of diverse nucleophiles (e.g.