NMR property calculations and experimental study of the 1,6-epoxycarvone and α-epoxypinene: a comparison of models

This work aims at using theoretical calculations of shielding tensors (σ) through different methods [gauge‐independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and individual gauges for atoms in molecules (IGAIM)] and spin‐spin coupling constants J using GIAO method to compare these methods and to corroborate the data obtained with the assignment of all of 1H and 13C NMR signals and the relative stereochemistry of the 1,6‐epoxycarvone and the α‐epoxypinene. All the 1H and 13C NMR signals were assigned unequivocally. The stereochemistry for the epoxides is trans and the B3LYP theory level with CSGT and IGAIM methods is the best choice to evaluate theoretical chemical shifts for compounds studied. Copyright © 2011 John Wiley & Sons, Ltd. Theoretical calculations of shielding tensors through different methods and J using GIAO method were used to compare these methods and to corroborate the data obtained with the assignment of all of 1H and 13C NMR signals of the 1,6‐epoxycarvone and the a‐epoxypinene.