Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
J Am Chem Soc. 2021 Mar 17;143(10):3918-3926. doi: 10.1021/jacs.0c13401. Epub 2021 Mar 3.
The cycloadditions of cyclopentadiene and cycloheptatriene with tropone are some of the earliest published examples of [6+4] cycloaddition reactions. We report quantum mechanical studies (ωB97X-D and DLPNO-CCSD(T)) of transition structures and products of these reactions, as well as quasi-classical molecular dynamics simulations of reaction trajectories. The study reveals that these cycloadditions involve ambimodal transition states resulting in a web of products by pericyclic interconversion pathways. Combined with these studies, calculations of simple parent systems and a thorough meta-analysis of literature examples reveal the general concept that all -[6+4] cycloadditions are ambimodal.
环戊二烯和环庚三烯与三亚甲基苯醌的环加成是最早发表的[6+4]环加成反应实例之一。我们报告了这些反应的过渡态和产物的量子力学研究（ωB97X-D 和 DLPNO-CCSD(T)），以及反应轨迹的准经典分子动力学模拟。研究表明，这些环加成涉及双模态过渡态，通过周环互变途径导致产物网络。结合这些研究，对简单母体系统的计算和对文献实例的全面荟萃分析揭示了一个普遍概念，即所有的[6+4]环加成都是双模态的。
