本文报道了[ n ]环对亚苯基(CPP)的溴化。较小的[ n ] CPPs(n <8)进行了高位点的双溴加成反应,以中等至极好的收率生产四溴加合物。理论计算表明,热力学稳定性决定了反应的反应性和位点选择性。通过FeBr 3催化的位点选择性溴化反应将加成产物进一步转化为八溴代产物。然后将四溴和八溴加合物转化为单溴到四溴CPP,然后再将其转化为几种CPP衍生物。因此,溴化和随后的转化为CPP的后期功能化提供了一条途径。
The synthesis of highly strained [5]cycloparaphenylene ([5]CPP), a structural unit of the periphery of C-60 and the shortest possible structural constituent of the sidewall of a (5,5) carbon nanotube, was achieved in nine steps in 17% overall yield. The synthesis relied on metal-mediated ring closure of a triethylsilyl (TES)-protected masked precursor 1c followed by removal of the TES groups and subsequent reductive aromatization. UV-vis and electrochemical studies revealed that the HOMO-LUMO gap of [5]CPP is narrow and is comparable to that of C-60, as predicted by theoretical calculations. The results suggest that [5]CPP should be an excellent lead compound for molecular electronics.