Synthesis of dithia[3.3]biphenyleno(2,2′)(1,2)-, (1,3)-, (1,4)cyclophanes and their atropisomerism and dynamic stereochemistry
作者:Yee-Hing Lai、Siew-Ying Wong、Darryl Hsieh-Yao Chang
DOI:10.1016/s0040-4020(01)86268-2
日期:1993.1
The dithiacyclophanes (1), (2), (3) and (4) were prepared by intermolecular cyclization reactions under high dilution conditions. Detailed 1H NMR spectroscopic analyses and dynamic NMR studies have indicated that pseudo-rotation of the biphenyl unit is restricted up to a temperature of 443K in (1), (2) and (3) involving energy barriers estimated to be > 75 kJ mol−1. At room temperature, a flipping
通过在高稀释条件下的分子间环化反应制备二噻吩环酮(1),(2),(3)和(4)。详细的1 H NMR光谱分析和动态NMR研究表明,在(1),(2)和(3)中,联苯单元的假旋转被限制在443K的温度范围内,其中涉及的势垒估计大于75 kJ mol。-1。然而,根据对一维和二维1中芳族质子的分析,在室温下,(1)和(2)中1,3-桥环的翻转过程很明显。1 H NMR谱。二硫代环烷(4)在构象上证明是三个成员中最易移动的,并且表现出两步构象过程,其中包括首先进行1,2桥环的反转过程,然后进行联苯部分的假旋转(消旋),在高温下的活化自由能估计为61.9 kJ mol -1。