Quantum chemical calculation of chemical shifts in the stereochemical determination of organic compounds: A practical approach

Abstract

In this chapter, we report an integrated approach of NMR and quantum mechanical calculation for the determination of the relative configuration of natural products. The entire protocol is described starting from building the investigated compound to the calculation of NMR properties at quantum theory level and the interpretation of the results. Each step of the protocol is described, and the main applied methods are reported. We report, as case studies, the determination of the relative configuration of two natural products: bonannione B isolated from Bonannia graeca, and callipeltin A isolated from the sponges Callipelta sp. and Latrunculia sp. Through the analysis of these natural products, we show the use of 13C chemical shift and homo and hetero J coupling constants, respectively, as an important tool in the interpretation of the experimental data for the determination of the relative configuration of organic compounds.