Cross-Fitting of Residual Dipolar Couplings

Residual dipolar couplings (RDCs) are important NMR-parameters for the structure determination of organic molecules. In this article we describe how RDCs can be used to effectively transfer structural information by cross-fitting the anisotropic parameters of molecules with similar overall structure. Using the example of 5- -cholestan-3-one and cho- lesterol, it is possible to distinguish diastereomers of the compounds by cross-fitting with transferred alignment tensors, even when strongly reduced subsets of RDCs are used. It is also demonstrated that RDCs can be used for direct cross- fitting even in flexible parts of the molecules that are sufficiently similar in structure and dynamic behavior. The cross- fitting approach as a general tool is discussed in details.