Overcrowded Triply Fused Carbo[7]helicene

This paper presents the synthesis and comprehensive analysis of a highly contorted and doubly negatively curved multihelicene compound, composed of three carbo[7]helicene units fused within a central six-membered ring. The synthesis of this compound involved a [2 + 2 + 2] cycloaddition reaction of 13,14-picyne, employing a Ni(0) catalyst, which exhibited superior performance compared to conventional Pd(0) catalysts. The evaluation of aromaticity in this triple carbo[7]helicene, utilizing magnetic and electronic criteria, led to noteworthy insights challenging the limitations of Clar’s model of aromaticity.本文报道了一种高度扭曲且兼具双重负曲率的多螺烯化合物的合成与全面分析，该化合物由三个碳[7]螺烯（carbo[7]helicene）单元稠合于中心六元环内构成。该化合物的合成以13,14-二炔为底物，通过[2+2+2]环加成反应实现，所用零价镍（Ni(0)）催化剂的性能优于传统的零价钯（Pd(0)）催化剂。通过磁学判据与电子学判据对该三重碳[7]螺烯的芳香性进行评估，所得关键发现挑战了克拉芳香性模型（Clar’s model of aromaticity）的局限性。