Oxidation of a thiophene-hexapyrrane hybrid S-P6 afforded a stable conjugated open-chain thiaheptapyrrolic helix 1 with the terminal thiophene and confused pyrrole units lying at a long distance that is adverse for further cyclization. Chelation of 1 with copper(II) ion afforded 1-Cu, which exhibits more distant terminal units. Interestingly, further oxidation of 1 triggered an intramolecular C-N fusion reaction to afford a unique 5,5,5-tricyclic fused linear thiaheptapyrrin 2, with the two terminals positioned in proximity, which favors the oxidative ring-closure reaction to give a unique 5,5,5-tricyclic fused thiaheptaphyrin (1.1.1.1.1.1.0) 3 under air. The inner-fusion strategy for positioning the reactive sites in proximity to promote oxidative cyclization offers a new approach for constructing large porphyrinoids through conjugated oligopyrrins without the assistance of metal ions.

中文翻译：

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从螺旋寡吡喃杂化物中合理合成5,5,5-三环稠合硫杂庚酸（1.1.1.1.1.1.0）。

噻吩-六吡喃杂化物S-P6的氧化可得到稳定的共轭开环噻庚并吡咯螺旋1，末端噻吩和吡咯单元的距离较长，这不利于进一步环化。1与铜（II）离子的螯合得到1-Cu，它具有更远的末端单元。有趣的是，进一步氧化1会触发分子内CN融合反应，从而产生独特的5,5,5-三环稠合线性硫庚啶2，两个末端均位于附近，这有利于氧化闭环反应产生独特的5，空气中的5,5-三环稠合硫庚七素（1.1.1.1.1.1.0）3