Magn Reson Chem. 2011 Mar;49(3):140-6. doi: 10.1002/mrc.2722. Epub 2011 Jan 28.
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 (1)H and (13)C NMR signals and the relative stereochemistry of the 1,6-epoxycarvone and the α-epoxypinene. All the (1)H and (13)C 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.
这项工作旨在使用屏蔽张量（σ）的理论计算通过不同的方法[无规规范原子轨道（GIAO），连续规范变换集（CSGT）和分子中原子的个别规范（IGAIM）]和使用 GIAO 方法的自旋-自旋偶合常数 J 来比较这些方法，并证实通过分配（1）H 和（13）C NMR 信号以及 1,6-环氧蒈酮和α-环氧蒎烯的相对立体化学来获得的数据。所有（1）H 和（13）C NMR 信号都被明确分配。环氧化物的立体化学为反式，并且 B3LYP 理论水平与 CSGT 和 IGAIM 方法是评估所研究化合物理论化学位移的最佳选择。
