Configurational Analysis by Residual Dipolar Couplings: Critical Assessment of "Structural Noise" from Thermal Vibrations.

The certainty of configurational assignments of natural products based on anisotropic NMR parameters, such as residual dipolar couplings (RDCs), must be amended by estimates on structural noise emerging from thermal vibrations. We show that vibrational analysis significantly affects the error margins with which RDCs can be back-calculated from molecular models, and the implications of thermal motions on the differentiability of diastereomers are derived.