Synthesis of novel redox systems having thiophenes highly integrated with quinone methides structure

我们对所有氢原子都被2，6-di-tert-butyl-4-methylenecyclohexa-2，5-dienone(苯醌-甲醚)结构取代的共轭噻吩类体系很感兴趣。我们已经制备了噻吩衍生物和联噻吩衍生物(我们分别将它们命名为“四喹硫烯”(1)和“六喹双硫烯”(2))。这在动态多级氧化还原体系和采用硫原子的交叉共轭体系方面引起了人们的关注。以溴并噻吩衍生物为原料，经Suzuki-Miyaura偶联反应合成了化合物1和2。通过X-射线分析确定了1的结构。中心五元环呈扭曲船状构象，没有发生扭键扭转。用循环伏安法检测了化合物1和2的电化学性质，并观察到它们的第一还原波不可逆。它表明构象发生了变化，单电子还原约为1和2。

We have been interested in conjugated thiophene systems whose all hydrogen atoms are substituted by 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone (quinone-methide) structure. We have prepared thiophene and bithiophene derivatives (we named them "tetraquinothiophene"(1) and "hexaquinobithiohene"(2), respectively). These attract attention in term of dynamic multi-stage redox system as well as cross conjugated system adopting sulfur atom. Compounds 1 and 2 were synthesized from bromothiophene derivatives via Suzuki-Miyaura coupling. The structure of 1 was determined by X-ray analysis. There were little torsion of pinch-bonds and central five membered ring formed twist boat like conformation. The electrochemical properties of 1 and 2 were examined by cyclic voltammetry and the first reduction waves of them were observed irreversibly. It indicates conformational changes occur with one-electron reduction about both 1 and 2.