In this presentation we describe the single-step preparation of a cyclic tetramer of acenaphthylene, known as tridecacyclene, through a cyclotetramerization reaction of 1-acenaphthenone. This previously unexplored cyclic tetramer differs from the better-known cyclic trimer, decacyclene, due to the presence of a central eight-membered ring. This ring not only forces the molecule to distort significantly from planarity, but is also responsible for its unique electronic properties, including a decrease in the reduction potential (by approximately 0.4 eV) and optical gap (by approximately 0.7 eV), compared to the more planar decacyclene. The radical anion and dianion of tridecacyclene have been prepared by reduction with potassium metal. Analysis of the solid-state structure of the dipotassium salt of the dianion reveals evidence of increased aromatic character within the structure's central 8-membered ring despite preservation of the tub-like shape inherent to its neutral parent. FInally, the synthesis of unsymmetrically functionalized derivatives of tridecacylene from symmetrical precursors reveals that the mechanism does not proceed through an expected aldol cyclization reaction; alternate methodology that we've explored provides some insight into this mechanism.

Tridecacyclene: Synthesis, properties, and aromaticity of a congested cyclooctatetraene

255th National Meeting (2018)

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