Expanded Helicenes: A General Synthetic Strategy and Remarkable Supramolecular and Solid-State Behavior
Expanded Helicenes: A General Synthetic Strategy and Remarkable Supramolecular and Solid-State Behavior
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DOI：
10.1021/jacs.7b10902
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发表时间：
2017-12-27
影响因子：
15
通讯作者：
Tilley, T. Don
中科院分区：
文献类型：
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作者：
Kiel, Gavin R.;Patel, Sajan C.;Tilley, T. Don
发散的合成策略允许获得一类新的螺旋烯的几个成员，“扩展的螺旋烯”，其由交替的线性和角度稠合的环组成。该策略是基于一个三倍，部分分子间[2+2+n]（n = 1或2）环加成与基板含有三个二炔单元。聚集行为的调查，无论是在溶液中和在固体状态下，揭示了这些化合物之一形成一个不寻常的纯手性，π-堆叠的二聚体通过一个平衡，这是缓慢的NMR时间尺度。利用该方法的多功能性来获得硒吩成环的膨胀螺烯，与其benzannulated类似物相反，其在固态下表现出长程堆积。新的螺烯具有低的外消旋障碍，如动态H-1 NMR光谱所示。
A divergent synthetic strategy allowed access to several members of a new class of helicenes, the "expanded helicenes", which are composed of alternating linearly and angularly fused rings. The strategy is based on a three-fold, partially intermolecular [2+2+n] (n = 1 or 2) cycloaddition with substrates containing three diyne units. Investigation of aggregation behavior, both in solution and in the solid state, revealed that one of these compounds forms an unusual homochiral, pi-stacked dimer via an equilibrium that is slow on the NMR time scale. The versatility of the method was harnessed to access a selenophene-annulated expanded helicene that, in contrast to its benzannulated analogue, exhibits long-range stacking in the solid state. The new helicenes possess low racemization barriers, as demonstrated by dynamic H-1 NMR spectroscopy.