ADDRESSING STEREOCHEMISTRY OF HETEROCYCLIC COMPOUNDS BY DFT NMR CALCULATIONS

Аннотация

This minireview aims to concisely present the state of the art from 2013 to 2017 in the joint application of a computational and experimental NMR approach to the stereostructural analysis of heterocyclic compounds. Despite being endowed with a limited number of degrees of freedom, heterocyclic compounds pose major conformational problems associated with the correct assessment of the ring puckering. Once the compound conformational preferences are defined, the main magnetic parameters (chemical shifts and coupling constants) can be predicted at various theoretical levels, with different computational costs, mainly depending on chosen number of conformers, method, functional, basis set, solvation model, and reference. To evaluate the performance of computational tools in determining relative configurations, beyond the classical statistical correlation parameters (R2, MAE, CMAE, ATE, RMSD), more sophisticated strategies were recently introduced, such as DP4, DP4+, and DP4 probability.