The use of NMR methods based on quantum mechanics to complement and guide the assignment of connectivity and stereochemistry of natural and artificial products has grown significantly. One of the unresolved challenges relates to the incorrect calculation of the conformational map of flexible molecules containing functional groups capable of generating a complex network of intramolecular hydrogen bond (IHB) interactions. In this context, the most popular and affordable DFT methods tend to overestimate the stability of conformations with multiple IHBs, even when standard implicit solvent models are used. Conformational distributions may not be realistic in protic solvents, negatively impacting the accuracy of calculated NMR δ values. Therefore, for polyhydroxylated molecules, the obtained results are often suboptimal, necessitating the development of a solution since hydroxyl groups are common functional groups in marketed drugs.
Relation to Green Chemistry:
Computational chemistry significantly advances green chemistry by reducing the reliance on chemical reagents, solvents, and the generation of experimental waste. Techniques such as quantum mechanical calculations and density functional theory (DFT) enable accurate predictions of molecular properties and spectroscopic data, minimizing environmental impact and resource consumption. Additionally, computationally assisted structure elucidation eliminates the need for excessive experimental trials, adhering to the principles of waste prevention and atom economy. These methods not only enhance the efficiency and safety of chemical research but also promote sustainable practices in alignment with green chemistry objectives.