Abstract：
An atropisomerism of large cycloarylenes was studied using [n]cyclo-4,10-pyrenylenes (n=6-21) as an illustrative example with two simple assumptions: (1) alternating configurations (R,S,R,S,…) are thermodynamically most stable, and (2) three consecutive identical configurations (R,R,R or S,S,S) are prevented. Ni-mediated coupling of a 5,9-diiodopyrene gave a series of directly-linked cyclic pyrene oligomers in one-pot reaction. As-synthesized cyclic hexamer was assigned as an (R,S,S,R,R,S) structure, converted into an (R,S,R,S,R,S)-form upon heating. Cyclic heptamer consists of two types of C2 symmetric structures predicted from assumption (2), one of which was convergent to one another by heating. Three atropisomers of cyclic octamer were analyzed from the possible five candidates by means of 1 H nuclear magnetic resonance (NMR) spectroscopy, and the conversion process to (R,S,R,S,R,S,R,S) configurations upon heating was investigated. In total, according to two simple rules, the analysis of atropisomerism could be performed smoothly.
摘要：
使用[n]环-4,10-pyrene（n=6-21）作为说明性示例，研究了大环芳基的阻转异构现象，并给出了两个简单的假设：（1）交替构型（R，S,R,S,,,)是热力学上最稳定的，和（2）三个连续的相同配置（R，R,R或S，S,S）被阻止。Ni介导的5,9-二碘芘偶联在一锅反应中产生了一系列直接连接的环状芘低聚物。合成后的环状六聚体被指定为(R，S,S,R,R,S)结构，转换成(R，S,R,S,R,S)-在加热时形成。环状七聚体由两种类型的C2对称结构组成，由假设（2）预测，其中一个通过加热相互会聚。通过1H核磁共振（NMR）光谱从可能的五种候选物中分析了环状八聚体的三种阻转异构体，和转换过程为(R，S,R,S,R,S,R,研究了加热时的S)构型。总的来说,根据两个简单的规则，反异构现象的分析可以顺利进行。
