Partial Alignment for Structure Determination of Organic Molecules

NMR spectroscopy is the most important method for structure elucidation in solution. Once the atomic connectivity is established (constitution of the molecule) the proof of stereochemistry is the next step. NMR as an achiral method provides only relative stereochemical information unless chiral environments (solvents, interaction with shift reagents, chemical modification via chiral auxiliaries) are used. For determining the relative stereochemistry, the classical parameters are NOE effects and J coupling constants. Only recently, two different new sources of stereochemical information have been introduced for biomolecules: cross-correlated relaxation [1] andresidual dipolar couplings (RDCs) [2,3]. We will here consider the application of RDCs for small molecules such as drugs or drug-like molecules.