Synthesis of Pentathiepanes and Isolation of the Conformers Based on High Inversion Barrier of the Pentathiepane Ring
作者:Yoshiaki Sugihara、Hitoshi Takeda、Juzo Nakayama
DOI:10.1002/(sici)1099-0690(199903)1999:3<597::aid-ejoc597>3.0.co;2-#
日期:1999.3
2-a]acenaphthylene (1) was sulfurated with elemental sulfur to give a pentathiepane derivative (2). A dynamic NMR spectrum analysis revealed that the two naphthalene rings of 2 are chemically nonequivalent up to 100 °C. The pentathiepane ring of 2 was shown to adopt a chair conformation both in solution and crystals. In accordance with the NMR spectrum analysis, the sulfuration of 5-phenylacenaphtho[1
Acenaphtho[1,2-a]acenaphthylene (1) 用元素硫硫化得到五噻吩衍生物 (2)。动态 NMR 光谱分析表明,2 的两个萘环在高达 100 °C 的温度下在化学上是不等价的。2的pentathiepane环在溶液和晶体中均显示为椅子构象。根据核磁共振谱分析,5-苯基苊并[1,2-a]苊(12)的硫化得到一对构象异构体(16a和16b),它们以纯形式分离。2 的 Friedel-Crafts 乙酰化,然后用 1,2-乙二硫醇进行二硫缩醛化,也得到一对可分离的构象异构体(18a 和 18b)。由于环反转,这两对构象异构体在室温下以一级动力学在溶液中彼此异构化。这个过程的激活参数,确定了 Ea、ΔH# 和 ΔS#。基于实验观察,提出了反演过程的可能机制。