A fruitful debate took place recently in literature, discussing the enhanced Diels–Alder reactivity of tropone derivatives for which the carbonyl polarity was reversed by means of umpolung. Karas et al. sustained that the umpolung increases the antiaromatic character of the ring, affecting the highest occupied molecular orbital (HOMO)/least unoccupied molecular orbital (LUMO) energies, speeding up the reaction. Tiekink et al. challenged this interpretation by sustaining that the asynchronicity of the reaction mechanisms, rather than orbital energy perturbation, was the main responsible for the smaller reaction barriers. We shed light on this dispute by computing full interaction quantum atom (IQA) and quantum theory of atoms in molecules (QTAIM) analyses over complete intrinsic reaction coordinate (IRC) paths for the Diels–Alder reaction of tropone and its umpolung derivatives, using the same systems studied by Karas et al. and Tiekink et al. Our results confirm that the asynchronicity is indeed very high for those reactions with smaller reaction barriers and offer an atom-by-atom and bond-by-bond analysis of the entire IRC pathways. Even though asynchronicity and lower reactions barriers seem to be related, antiaromaticity and lower barriers are related as well, but discussing both these interpretations does not necessarily require arguments on HOMO/LUMO energies to be invoked.

中文翻译：

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umpolung tropone 增加的 Diels-Alder 反应性：使用 QTAIM 和 IQA 沿着完整的 IRC 路径分析单个原子和键

最近在文献中进行了一场富有成果的辩论，讨论了托酮衍生物的增强的狄尔斯-阿尔德反应性，其中羰基极性通过反极性反转。卡拉斯等人。坚持认为umpolung增加了环的反芳香特性，影响最高占据分子轨道（HOMO）/最少未占据分子轨道（LUMO）能量，加速反应。蒂金克等人。通过坚持认为反应机制的异步性而不是轨道能量扰动是造成较小反应势垒的主要原因，对这种解释提出了挑战。我们通过计算全相互作用量子原子（IQA）和分子中原子量子理论（QTAIM）对托酮及其反推衍生物的狄尔斯-阿尔德反应的完整本征反应坐标（IRC）路径进行分析，阐明了这一争议，使用Karas 等人研究的相同系统。和蒂金克等人。我们的结果证实，对于那些反应势垒较小的反应来说，异步性确实非常高，并提供了整个 IRC 途径的逐原子和逐键分析。尽管异步性和较低的反应能垒似乎相关，反芳香性和较低的能垒也相关，但讨论这两种解释并不一定需要引用 HOMO/LUMO 能量的争论。和蒂金克等人。我们的结果证实，对于那些反应势垒较小的反应来说，异步性确实非常高，并提供了整个 IRC 途径的逐原子和逐键分析。尽管异步性和较低的反应能垒似乎相关，反芳香性和较低的能垒也相关，但讨论这两种解释并不一定需要引用 HOMO/LUMO 能量的争论。和蒂金克等人。我们的结果证实，对于那些反应势垒较小的反应来说，异步性确实非常高，并提供了整个 IRC 途径的逐原子和逐键分析。尽管异步性和较低的反应能垒似乎相关，反芳香性和较低的能垒也相关，但讨论这两种解释并不一定需要引用 HOMO/LUMO 能量的争论。