Department of Chemistry, King's College London, London SE1 1DB, UK.
Molecules. 2021 Aug 26;26(17):5162. doi: 10.3390/molecules26175162.
The physicochemical properties and reactivity of macrocycles are critically shaped by their conformations. In this work, we have identified seven conformations of the macrocyclic ketone cyclododecanone using chirped-pulse Fourier transform microwave spectroscopy in combination with ab initio and density functional theory calculations. Cyclododecanone is strongly biased towards adopting a square configuration of the heavy atom framework featuring three C-C bonds per side. The substitution and effective structures of this conformation have been determined through the observation of its C isotopologues. The minimisation of transannular interactions and, to a lesser extent, HCCH eclipsed configurations drive conformational preferences. Our results contribute to a better understanding of the intrinsic forces mediating structural choices in macrocycles.
大环的理化性质和反应活性受到其构象的严格控制。在这项工作中，我们使用啁啾脉冲傅里叶变换微波光谱结合从头算和密度泛函理论计算，确定了环十二酮的七种构象。环十二酮强烈偏向于采用每个边具有三个 C-C 键的重原子框架的正方形构象。通过观察其 C 同系物，确定了这种构象的取代和有效结构。构象偏好是由环间相互作用的最小化和在较小程度上 HCCH 重叠构象驱动的。我们的结果有助于更好地理解大环中调节结构选择的内在力。
