Harrington Laura E, Britten James F, Nikitin Kirill, McGlinchey Michael J
Department of Chemistry, McMaster University, Hamilton, ON, L8S 4M1, Canada.
School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
Chempluschem. 2017 Mar;82(3):433-441. doi: 10.1002/cplu.201600512. Epub 2017 Jan 19.
Treatment of β-naphthil dihydrazone, 1, with silver oxide yields di(β-naphthyl)acetylene, 2, which undergoes Diels-Alder cycloaddition with tetra(β-naphthyl)cyclopentadienone, 4, to give hexa(β-naphthyl)benzene, 5, upon decarbonylation. Molecules 1, 2 and 4 have been characterised by X-ray crystallography, but hexa(β-naphthyl)benzene exhibits rotational disorder of the peripheral substituents. Nevertheless, calculations at the density functional level reveal the favoured structure of 5 to be a molecular propeller, in which the eight possible rotamers are essentially iso-energetic. Variable-temperature NMR spectroscopy studies yield a naphthyl rotational barrier of approximately 17 kcal mol , similar to that previously found for meta-substituted phenyl groups. Enantiomerisation of hexa(β-naphthyl)benzene engendered by rotation of a single naphthyl ring has been studied by DFT calculations, and the process has been represented pictorially.
用氧化银处理β-萘二腙1，生成二（β-萘基）乙炔2，2与四（β-萘基）环戊二烯酮4发生狄尔斯-阿尔德环加成反应，脱羰后得到六（β-萘基）苯5。分子1、2和4已通过X射线晶体学进行了表征，但六（β-萘基）苯表现出外围取代基的旋转无序。尽管如此，密度泛函水平的计算表明5的有利结构是一个分子螺旋桨，其中八种可能的旋转异构体基本上具有等能量。变温核磁共振光谱研究得出萘基的旋转势垒约为17 kcal mol ，与之前发现的间位取代苯基的旋转势垒相似。通过密度泛函理论计算研究了由单个萘基环旋转引起的六（β-萘基）苯的对映异构化，并以图示方式展示了该过程。
