Cycloaddition catalyzed by transition metals such as rhodium (I) is an important way to synthesize functionalized molecules in medicinal chemistry. When the reagent has a saturated ring containing more than five carbons (or heavy atoms), the reaction can progress when the compound has an allenyl group, but not for a vinyl group. Here, we constructed two computational models for allenylcyclopentane-alkyne and vinylcyclopentane-alkyne, and obtained their reaction pathways using density functional theory (DFT). From the reaction pathways, we confirmed that the former model has a much lower reaction energy than the latter. We also found that the molecular orbitals of the transition state structure at the rate-controlling step contribute significantly to the difference in reactivity between the two models.

过渡金属如铑（I）催化的环加成反应是在药物化学中合成功能化分子的重要途径。当试剂的饱和环包含五个以上的碳（或重原子）时，当化合物具有一个烯基而不是乙烯基时，该反应可以进行。在这里，我们构建了烯丙基环戊烷-炔和乙烯基环戊烷-炔的两个计算模型，并使用密度泛函理论（DFT）获得了它们的反应途径。从反应路径中，我们证实了前者模型的反应能量比后者低得多。我们还发现，在速率控制步骤中过渡态结构的分子轨道对两个模型之间的反应性差异有显着贡献。