carbo‐Naphthalene: A Polycyclic carbo‐Benzenoid Fragment of α‐Graphyne

A ring carbo‐mer of naphthalene, C₃₂Ar₈ (Ar=p‐n‐pentylphenyl), has been obtained as a stable blue chromophore, after a 19‐step synthetic route involving methods inspired from those used in the synthesis of carbo‐benzenes, or specifically devised for the present target, like a double Sonogashira‐type coupling reaction. The last step is a SnCl₂/HCl‐mediated reduction of a decaoxy‐carbo‐decalin, which is prepared through successive 8+10] macrocyclization steps. Two carbo‐benzene references are also described, C₁₈Ar₆ and o‐C₁₈Ar₄(C≡C‐SiiPr₃)₂. The carbo‐naphthalene bicycle is locally aromatic according to structural and magnetic criteria, as revealed by strong diatropic ring current effects on the deshielding of ¹H nuclei of the Ar groups and on the negative value of the DFT‐calculated NICS at the center of the C₁₈ rings (?12.8 ppm). The stability and aromaticity of this smallest fused molecular fragment of α‐graphyne allows prediction of the same properties for the carbon allotrope itself.